diff --git a/.env.example b/.env.example
index 5cbc382..eb2bf94 100644
--- a/.env.example
+++ b/.env.example
@@ -30,7 +30,8 @@ SMS_GAMA_BASE_URL=https://sms.igama.ir/api/v1
 SMS_GAMA_USERNAME=
 SMS_GAMA_PASSWORD=
 SMS_GAMA_SOURCE_SERVICE=5000110005
-# Optional later: SMS_GAMA_SOURCE_ADVERTISE=500099000005
+# Optional later: SMS_GAMA_SOURCE_ADVERTISE=5000990009
+SMS_GAMA_SOURCE_ADVERTISE=5000990009
 # Partner gateway: domain:apiKey pairs, comma-separated (www. is stripped)
 # Example: SMS_PARTNERS=baloutpastry.com:replace-with-long-random-secret
 SMS_PARTNERS=
diff --git a/src/auth/sms.service.ts b/src/auth/sms.service.ts
index 376f22a..0729ef8 100644
--- a/src/auth/sms.service.ts
+++ b/src/auth/sms.service.ts
@@ -10,6 +10,22 @@ export type SmsSendResult = {
   serverId: string;
 };
 
+export type SmsBulkSendResult = {
+  serverIds: string[];
+  recipientCount: number;
+};
+
+export type SmsSendOptions = {
+  /** Gama shortcode override. When omitted, uses SMS_GAMA_SOURCE_SERVICE. */
+  source?: string;
+};
+
+/** Default Meshkee advertising shortcode when a business has no own SMS number. */
+export const DEFAULT_ADVERTISING_SMS_SOURCE = '5000990009';
+
+/** Gama batch size limit is undocumented; keep chunks conservative. */
+const GAMA_BULK_CHUNK_SIZE = 100;
+
 type GamaQuickResponse = {
   success?: boolean;
   message?: string | null;
@@ -17,6 +33,13 @@ type GamaQuickResponse = {
   body?: number | string | null;
 };
 
+type GamaBulkResponse = {
+  success?: boolean;
+  message?: string | null;
+  errors?: unknown;
+  body?: Array<number | string> | null;
+};
+
 @Injectable()
 export class SmsService {
   private readonly logger = new Logger(SmsService.name);
@@ -27,6 +50,14 @@ export class SmsService {
     return this.config.get<string>('SMS_ENABLED', 'false') === 'true';
   }
 
+  /** Advertising / customer-broadcast fallback shortcode. */
+  getAdvertisingSource(): string {
+    return (
+      this.config.get<string>('SMS_GAMA_SOURCE_ADVERTISE')?.trim() ||
+      DEFAULT_ADVERTISING_SMS_SOURCE
+    );
+  }
+
   async sendVerificationCode(
     cellNumber: string,
     code: string,
@@ -46,7 +77,11 @@ export class SmsService {
     return this.sendMessage(cellNumber, message);
   }
 
-  async sendMessage(cellNumber: string, message: string): Promise<SmsSendResult> {
+  async sendMessage(
+    cellNumber: string,
+    message: string,
+    options?: SmsSendOptions,
+  ): Promise<SmsSendResult> {
     if (!this.isEnabled()) {
       this.logger.warn(`SMS disabled — message for ${cellNumber} not sent: ${message}`);
       return { serverId: 'disabled' };
@@ -65,11 +100,78 @@ export class SmsService {
       throw new BadRequestException('Invalid cellphone number');
     }
 
+    const sourceOverride = options?.source?.trim() || undefined;
+
+    // Local proxy path has no per-sender shortcode unless we pass source through.
     if (this.isProxyConfigured()) {
-      return this.sendViaProxy(destination, text);
+      return this.sendViaProxy(destination, text, sourceOverride);
     }
 
-    return this.sendQuick(destination, text);
+    return this.sendQuick(destination, text, sourceOverride);
+  }
+
+  /**
+   * One message → many destinations via Gama SendBulk (`/send/bulk`).
+   * Falls back to sequential SendQuick / proxy when only one number or proxy is configured.
+   */
+  async sendBulkMessage(
+    cellNumbers: string[],
+    message: string,
+    options?: SmsSendOptions,
+  ): Promise<SmsBulkSendResult> {
+    if (!this.isEnabled()) {
+      this.logger.warn(
+        `SMS disabled — bulk message for ${cellNumbers.length} recipients not sent: ${message}`,
+      );
+      return { serverIds: ['disabled'], recipientCount: cellNumbers.length };
+    }
+
+    const text = message.trim();
+    if (!text) {
+      throw new BadRequestException('Message is empty');
+    }
+    if (text.length > 700) {
+      throw new BadRequestException('Message is too long (max 700 characters)');
+    }
+
+    const destinations: string[] = [];
+    const seen = new Set<string>();
+    for (const raw of cellNumbers) {
+      const msisdn = toGamaMsisdn(raw);
+      if (!msisdn || seen.has(msisdn)) continue;
+      seen.add(msisdn);
+      destinations.push(msisdn);
+    }
+
+    if (destinations.length === 0) {
+      throw new BadRequestException('No valid cellphone numbers to send to');
+    }
+
+    const sourceOverride = options?.source?.trim() || undefined;
+
+    if (destinations.length === 1) {
+      const single = await this.sendMessage(destinations[0], text, options);
+      return { serverIds: [single.serverId], recipientCount: 1 };
+    }
+
+    // Local proxy only supports single destination — send sequentially.
+    if (this.isProxyConfigured()) {
+      const serverIds: string[] = [];
+      for (const destination of destinations) {
+        const result = await this.sendViaProxy(destination, text, sourceOverride);
+        serverIds.push(result.serverId);
+      }
+      return { serverIds, recipientCount: destinations.length };
+    }
+
+    const serverIds: string[] = [];
+    for (let i = 0; i < destinations.length; i += GAMA_BULK_CHUNK_SIZE) {
+      const chunk = destinations.slice(i, i + GAMA_BULK_CHUNK_SIZE);
+      const chunkIds = await this.sendBulk(chunk, text, sourceOverride);
+      serverIds.push(...chunkIds);
+    }
+
+    return { serverIds, recipientCount: destinations.length };
   }
 
   private isProxyConfigured(): boolean {
@@ -80,7 +182,11 @@ export class SmsService {
   }
 
   /** Local-dev path: deliver via remote Meshkee partner SMS gateway (production reaches Gama). */
-  private async sendViaProxy(destination: string, message: string): Promise<SmsSendResult> {
+  private async sendViaProxy(
+    destination: string,
+    message: string,
+    source?: string,
+  ): Promise<SmsSendResult> {
     const url = this.config.get<string>('SMS_PROXY_URL')!.trim();
     const apiKey = this.config.get<string>('SMS_PROXY_API_KEY')!.trim();
     const domain = this.config.get<string>('SMS_PROXY_DOMAIN')!.trim();
@@ -99,6 +205,7 @@ export class SmsService {
           domain,
           to: destination,
           message,
+          ...(source ? { source } : {}),
         }),
         signal: AbortSignal.timeout(20_000),
       });
@@ -144,10 +251,16 @@ export class SmsService {
     return { serverId };
   }
 
-  private async sendQuick(destination: string, message: string): Promise<SmsSendResult> {
+  private async sendQuick(
+    destination: string,
+    message: string,
+    sourceOverride?: string,
+  ): Promise<SmsSendResult> {
     const username = this.config.get<string>('SMS_GAMA_USERNAME')?.trim();
     const password = this.config.get<string>('SMS_GAMA_PASSWORD')?.trim();
-    const source = this.config.get<string>('SMS_GAMA_SOURCE_SERVICE')?.trim();
+    const source =
+      sourceOverride?.trim() ||
+      this.config.get<string>('SMS_GAMA_SOURCE_SERVICE')?.trim();
     const baseUrl = (
       this.config.get<string>('SMS_GAMA_BASE_URL') ?? 'https://sms.igama.ir/api/v1'
     ).replace(/\/$/, '');
@@ -209,9 +322,97 @@ export class SmsService {
       throw new ServiceUnavailableException('SMS provider returned an empty server id');
     }
 
-    this.logger.log(`SMS sent to ${masked} via Gama (serverId=${serverId})`);
+    this.logger.log(
+      `SMS sent to ${masked} via Gama source=${source} (serverId=${serverId})`,
+    );
     return { serverId };
   }
+
+  /** Gama SendBulk — one message, many MSISDNs (`destinations` array). */
+  private async sendBulk(
+    destinations: string[],
+    message: string,
+    sourceOverride?: string,
+  ): Promise<string[]> {
+    const username = this.config.get<string>('SMS_GAMA_USERNAME')?.trim();
+    const password = this.config.get<string>('SMS_GAMA_PASSWORD')?.trim();
+    const source =
+      sourceOverride?.trim() ||
+      this.config.get<string>('SMS_GAMA_SOURCE_SERVICE')?.trim();
+    const baseUrl = (
+      this.config.get<string>('SMS_GAMA_BASE_URL') ?? 'https://sms.igama.ir/api/v1'
+    ).replace(/\/$/, '');
+
+    if (!username || !password || !source) {
+      this.logger.error('SMS provider credentials are not configured');
+      throw new ServiceUnavailableException('SMS provider is not configured yet');
+    }
+
+    const url = `${baseUrl}/send/bulk`;
+
+    let response: Response;
+    try {
+      response = await fetch(url, {
+        method: 'POST',
+        headers: {
+          Accept: 'application/json',
+          'Content-Type': 'application/json',
+        },
+        body: JSON.stringify({
+          username,
+          password,
+          message,
+          source,
+          destinations,
+          delay: 0,
+          expire: null,
+        }),
+        signal: AbortSignal.timeout(30_000),
+      });
+    } catch (err) {
+      this.logger.error(
+        `Gama SendBulk network error for ${destinations.length} recipients: ${
+          err instanceof Error ? err.message : err
+        }`,
+      );
+      throw new ServiceUnavailableException('SMS provider is unreachable');
+    }
+
+    let payload: GamaBulkResponse;
+    try {
+      payload = (await response.json()) as GamaBulkResponse;
+    } catch {
+      this.logger.error(
+        `Gama SendBulk returned non-JSON for ${destinations.length} recipients (HTTP ${response.status})`,
+      );
+      throw new ServiceUnavailableException('SMS provider returned an invalid response');
+    }
+
+    if (!response.ok || !payload.success) {
+      const providerMessage =
+        typeof payload.message === 'string' && payload.message.trim()
+          ? payload.message.trim()
+          : `HTTP ${response.status}`;
+      this.logger.warn(
+        `Gama SendBulk failed for ${destinations.length} recipients: ${providerMessage}`,
+      );
+      throw mapGamaError(providerMessage);
+    }
+
+    const body = Array.isArray(payload.body) ? payload.body : [];
+    const serverIds = body.map((id) => String(id)).filter(Boolean);
+    if (serverIds.length === 0) {
+      this.logger.warn(
+        `Gama SendBulk succeeded without serverIds for ${destinations.length} recipients`,
+      );
+      throw new ServiceUnavailableException('SMS provider returned an empty server id');
+    }
+
+    this.logger.log(
+      `SMS bulk sent to ${destinations.length} via Gama source=${source} (ids=${serverIds.length})`,
+    );
+    return serverIds;
+  }
 }
 
 /** Accept 09… / 9… / +989… / 989… → Gama MSISDN `989…` (no plus). */
@@ -273,5 +474,8 @@ function mapGamaError(message: string): Error {
   if (lower.includes('message is empty')) {
     return new BadRequestException('Message is empty');
   }
+  if (lower.includes('maximum amount') || lower.includes('batch')) {
+    return new BadRequestException('Too many SMS destinations in one batch');
+  }
   return new ServiceUnavailableException('SMS provider rejected the request');
 }
diff --git a/src/business-admin/business-admin.service.ts b/src/business-admin/business-admin.service.ts
index 002427f..ded3bd5 100644
--- a/src/business-admin/business-admin.service.ts
+++ b/src/business-admin/business-admin.service.ts
@@ -26,10 +26,13 @@ import { LegacyPurgeService } from './legacy-purge.service';
 import { normalizeBusinessPrimaryColorId } from '../business-settings/business-primary-colors';
 import type { BusinessPrimaryColorId } from '../business-settings/business-primary-colors';
 import {
+  mergeBusinessSettings,
+  normalizeBusinessSettings,
   normalizeDashboardLocale,
   normalizeDashboardThemeMode,
   normalizeEnabledBusinessModules,
   normalizeHomeCharts,
+  normalizeSmsSenderNumber,
   toPrismaJson,
 } from '../business-settings/business-settings.util';
 import type {
@@ -77,6 +80,7 @@ type BusinessRow = {
   themeMode: string | null;
   enabledModules: unknown;
   homeCharts: unknown;
+  smsSenderNumber: string | null;
 };
 
 function slugify(value: string) {
@@ -161,7 +165,8 @@ export class BusinessAdminService {
           b.settings->'branding'->>'defaultLocale' AS "defaultLocale",
           b.settings->'branding'->>'themeMode' AS "themeMode",
           b.settings->'modules'->'enabled' AS "enabledModules",
-          b.settings->'modules'->'charts' AS "homeCharts"
+          b.settings->'modules'->'charts' AS "homeCharts",
+          b.settings->'sms'->>'senderNumber' AS "smsSenderNumber"
         FROM businesses b
         LEFT JOIN LATERAL (
           SELECT d.id, d.host, d.ssl_enabled, d.git_repo_url, d.deploy_slug
@@ -222,6 +227,7 @@ export class BusinessAdminService {
           enabledModules,
           moduleCount: enabledModules.length,
           homeCharts,
+          smsSenderNumber: normalizeSmsSenderNumber(item.smsSenderNumber),
         };
       }),
       total: totalRow[0]?.total ?? 0,
@@ -448,7 +454,33 @@ export class BusinessAdminService {
       await this.assertOldBusinessIdAvailable(BigInt(dto.oldBusinessId), businessId);
     }
 
+    if (dto.smsSenderNumber !== undefined) {
+      if (
+        dto.smsSenderNumber !== null &&
+        dto.smsSenderNumber !== '' &&
+        !normalizeSmsSenderNumber(dto.smsSenderNumber)
+      ) {
+        throw new BadRequestException(
+          'smsSenderNumber must be an 8–16 digit shortcode',
+        );
+      }
+    }
+
     await this.prisma.$transaction(async (tx) => {
+      const nextSettings =
+        dto.smsSenderNumber !== undefined
+          ? toPrismaJson(
+              mergeBusinessSettings(normalizeBusinessSettings(business.settings), {
+                sms: {
+                  senderNumber:
+                    dto.smsSenderNumber === null || dto.smsSenderNumber === ''
+                      ? null
+                      : normalizeSmsSenderNumber(dto.smsSenderNumber),
+                },
+              }),
+            )
+          : undefined;
+
       await tx.business.update({
         where: { id: businessId },
         data: {
@@ -470,6 +502,7 @@ export class BusinessAdminService {
                     : new Date(dto.annualRenewalAt),
               }
             : {}),
+          ...(nextSettings !== undefined ? { settings: nextSettings } : {}),
         },
       });
 
@@ -1238,6 +1271,7 @@ export class BusinessAdminService {
       annualRenewalAt: Date | null;
       createdAt: Date;
       updatedAt: Date;
+      settings: unknown;
       categoryAssignments: {
         category: {
           id: bigint;
@@ -1267,6 +1301,7 @@ export class BusinessAdminService {
     },
   ) {
     const owner = business.businessUsers[0]?.user ?? null;
+    const settings = normalizeBusinessSettings(business.settings);
 
     return {
       id: business.id,
@@ -1280,6 +1315,7 @@ export class BusinessAdminService {
       annualRenewalAt: business.annualRenewalAt,
       createdAt: business.createdAt,
       updatedAt: business.updatedAt,
+      smsSenderNumber: settings.sms.senderNumber,
       categories: business.categoryAssignments.map((a) => ({
         id: a.category.id,
         name: a.category.name,
diff --git a/src/business-admin/dto/update-business.dto.ts b/src/business-admin/dto/update-business.dto.ts
index a736818..44ee4ad 100644
--- a/src/business-admin/dto/update-business.dto.ts
+++ b/src/business-admin/dto/update-business.dto.ts
@@ -59,4 +59,16 @@ export class UpdateBusinessDto {
   @ValidateIf((_, value) => value !== null)
   @IsDateString()
   annualRenewalAt?: string | null;
+
+  /**
+   * Business SMS shortcode for customer messages (e.g. 5000123456).
+   * Empty string or null clears it (falls back to Meshkee advertising number).
+   */
+  @IsOptional()
+  @ValidateIf((_, value) => value !== null && value !== '')
+  @IsString()
+  @Matches(/^\d{8,16}$/, {
+    message: 'smsSenderNumber must be an 8–16 digit shortcode',
+  })
+  smsSenderNumber?: string | null;
 }
diff --git a/src/business-settings/business-settings.types.ts b/src/business-settings/business-settings.types.ts
index ab9d55d..697a2aa 100644
--- a/src/business-settings/business-settings.types.ts
+++ b/src/business-settings/business-settings.types.ts
@@ -195,6 +195,12 @@ export type ModulesSettings = {
   charts: [HomeChartId, HomeChartId];
 };
 
+/** Per-business SMS sender (Gama shortcode). Empty → Meshkee advertising number. */
+export type SmsSettings = {
+  /** Outbound shortcode for customer SMS, e.g. "5000123456". */
+  senderNumber: string | null;
+};
+
 /** Top-level business settings stored in `businesses.settings` JSONB. */
 export type BusinessSettings = {
   branding: BrandingSettings;
@@ -202,6 +208,7 @@ export type BusinessSettings = {
   store: StoreSettings;
   modules: ModulesSettings;
   website: WebsiteSettings;
+  sms: SmsSettings;
 };
 
 export const DEFAULT_ORDER_PROCESS_STEPS: OrderProcessStep[] = [
@@ -316,4 +323,7 @@ export const DEFAULT_BUSINESS_SETTINGS: BusinessSettings = {
   website: {
     specialProductsSource: 'store_item',
   },
+  sms: {
+    senderNumber: null,
+  },
 };
diff --git a/src/business-settings/business-settings.util.ts b/src/business-settings/business-settings.util.ts
index 19cbd79..904cffb 100644
--- a/src/business-settings/business-settings.util.ts
+++ b/src/business-settings/business-settings.util.ts
@@ -121,6 +121,16 @@ function readString(value: unknown, fallback = '') {
   return typeof value === 'string' ? value.trim() : fallback;
 }
 
+/** Gama / Iranian service shortcodes are numeric (e.g. 5000123456). */
+export function normalizeSmsSenderNumber(value: unknown): string | null {
+  if (value == null) return null;
+  if (typeof value !== 'string' && typeof value !== 'number') return null;
+  const digits = String(value).replace(/\D/g, '');
+  if (!digits) return null;
+  if (digits.length < 8 || digits.length > 16) return null;
+  return digits;
+}
+
 function isPaymentGatewayId(value: unknown): value is PaymentGatewayId {
   return (
     typeof value === 'string' &&
@@ -380,6 +390,7 @@ export function normalizeBusinessSettings(raw: unknown): BusinessSettings {
   const store = isRecord(source.store) ? source.store : {};
   const modules = isRecord(source.modules) ? source.modules : {};
   const website = isRecord(source.website) ? source.website : {};
+  const sms = isRecord(source.sms) ? source.sms : {};
   const hasModulesKey = Object.prototype.hasOwnProperty.call(source, 'modules');
   const enabledModules = hasModulesKey
     ? Array.isArray(modules.enabled)
@@ -431,6 +442,9 @@ export function normalizeBusinessSettings(raw: unknown): BusinessSettings {
       ),
       sitemapConfig: normalizeWebsiteSitemapConfig(website.sitemapConfig),
     },
+    sms: {
+      senderNumber: normalizeSmsSenderNumber(sms.senderNumber),
+    },
   };
 }
 
@@ -482,6 +496,12 @@ export function mergeBusinessSettings(
           ? patch.website.sitemapConfig
           : current.website.sitemapConfig,
     },
+    sms: {
+      senderNumber:
+        patch.sms?.senderNumber !== undefined
+          ? patch.sms.senderNumber
+          : current.sms.senderNumber,
+    },
   };
 }
 
diff --git a/src/customers/customers-excel.ts b/src/customers/customers-excel.ts
new file mode 100644
index 0000000..8b67c34
--- /dev/null
+++ b/src/customers/customers-excel.ts
@@ -0,0 +1,340 @@
+import { BadRequestException } from '@nestjs/common';
+import ExcelJS from 'exceljs';
+
+export const CUSTOMERS_SHEET_NAME = 'Customers';
+
+export const CUSTOMER_EXCEL_HEADERS = {
+  phone: 'phone',
+  firstName: 'first_name',
+  lastName: 'last_name',
+} as const;
+
+type HeaderKey = keyof typeof CUSTOMER_EXCEL_HEADERS;
+
+const HEADER_ALIASES: Record<string, HeaderKey> = {
+  phone: 'phone',
+  cell: 'phone',
+  cell_number: 'phone',
+  cellnumber: 'phone',
+  mobile: 'phone',
+  'mobile number': 'phone',
+  'phone number': 'phone',
+  شماره: 'phone',
+  'شماره موبایل': 'phone',
+  موبایل: 'phone',
+  first_name: 'firstName',
+  firstname: 'firstName',
+  'first name': 'firstName',
+  name: 'firstName',
+  نام: 'firstName',
+  last_name: 'lastName',
+  lastname: 'lastName',
+  'last name': 'lastName',
+  'نام خانوادگی': 'lastName',
+};
+
+const PERSIAN_DIGITS = '۰۱۲۳۴۵۶۷۸۹';
+const ARABIC_DIGITS = '٠١٢٣٤٥٦٧٨٩';
+const E164_RE = /^\+[1-9]\d{6,14}$/;
+
+export interface CustomerExcelRow {
+  phone: string;
+  firstName: string;
+  lastName: string;
+}
+
+export interface ParsedCustomerExcelRow {
+  rowNumber: number;
+  phone: string;
+  firstName: string | null;
+  lastName: string | null;
+}
+
+export async function buildCustomersExcel(rows: CustomerExcelRow[]): Promise<Buffer> {
+  const workbook = new ExcelJS.Workbook();
+  workbook.creator = 'Meshkee';
+  workbook.created = new Date();
+
+  const sheet = workbook.addWorksheet(CUSTOMERS_SHEET_NAME);
+  sheet.columns = [
+    { header: CUSTOMER_EXCEL_HEADERS.phone, key: 'phone', width: 16 },
+    { header: CUSTOMER_EXCEL_HEADERS.firstName, key: 'firstName', width: 18 },
+    { header: CUSTOMER_EXCEL_HEADERS.lastName, key: 'lastName', width: 20 },
+    { width: 3 },
+    { header: 'دستورالعمل', width: 48 },
+    { header: 'Instructions', width: 48 },
+  ];
+
+  const header = sheet.getRow(1);
+  header.height = 22;
+  header.font = { bold: true, size: 11 };
+  header.alignment = { vertical: 'middle' };
+  for (let col = 1; col <= 3; col += 1) {
+    const cell = header.getCell(col);
+    cell.fill = {
+      type: 'pattern',
+      pattern: 'solid',
+      fgColor: { argb: 'FFE8EEF7' },
+    };
+    cell.font = { bold: true, size: 11 };
+    cell.alignment = { vertical: 'middle' };
+  }
+  for (let col = 5; col <= 6; col += 1) {
+    const cell = header.getCell(col);
+    cell.font = { bold: true, size: 11 };
+    cell.alignment = { vertical: 'middle' };
+  }
+
+  for (const row of rows) {
+    const added = sheet.addRow({
+      phone: formatPhoneForExcel(row.phone),
+      firstName: row.firstName,
+      lastName: row.lastName,
+    });
+    added.height = 20;
+    added.font = { size: 11 };
+
+    const phoneCell = added.getCell('phone');
+    phoneCell.numFmt = '@';
+    phoneCell.alignment = { vertical: 'middle', readingOrder: 'ltr', horizontal: 'left' };
+
+    const firstNameCell = added.getCell('firstName');
+    firstNameCell.alignment = {
+      vertical: 'middle',
+      readingOrder: looksPersian(row.firstName) ? 'rtl' : 'ltr',
+    };
+
+    const lastNameCell = added.getCell('lastName');
+    lastNameCell.alignment = {
+      vertical: 'middle',
+      readingOrder: looksPersian(row.lastName) ? 'rtl' : 'ltr',
+    };
+  }
+
+  writeInstructionColumns(sheet);
+  sheet.views = [{ state: 'frozen', ySplit: 1, rightToLeft: false }];
+
+  const buffer = await workbook.xlsx.writeBuffer();
+  return Buffer.from(buffer);
+}
+
+export async function parseCustomersExcel(buffer: Buffer): Promise<ParsedCustomerExcelRow[]> {
+  const workbook = new ExcelJS.Workbook();
+  await workbook.xlsx.load(buffer as unknown as Parameters<ExcelJS.Xlsx['load']>[0]);
+
+  const sheet =
+    workbook.getWorksheet(CUSTOMERS_SHEET_NAME) ?? workbook.worksheets[0];
+
+  if (!sheet) {
+    throw new BadRequestException('Excel file has no worksheet.');
+  }
+
+  const headerMap = readHeaderMap(sheet);
+  const phoneCol = headerMap.phone;
+  if (!phoneCol) {
+    throw new BadRequestException(
+      'Excel is missing required column: phone (or cell / mobile / شماره).',
+    );
+  }
+
+  const firstNameCol = headerMap.firstName;
+  const lastNameCol = headerMap.lastName;
+  const rows: ParsedCustomerExcelRow[] = [];
+  const seenPhones = new Set<string>();
+
+  sheet.eachRow((row, rowNumber) => {
+    if (rowNumber === 1) return;
+
+    const rawPhone = cellText(row.getCell(phoneCol).value);
+    const firstName = firstNameCol
+      ? optionalName(cellText(row.getCell(firstNameCol).value))
+      : null;
+    const lastName = lastNameCol
+      ? optionalName(cellText(row.getCell(lastNameCol).value))
+      : null;
+
+    if (!rawPhone && !firstName && !lastName) return;
+
+    if (!rawPhone) {
+      throw new BadRequestException(`Row ${rowNumber}: phone is required.`);
+    }
+
+    const phone = normalizeCellToE164(rawPhone);
+    if (!phone) {
+      throw new BadRequestException(
+        `Row ${rowNumber}: phone "${rawPhone}" is not a valid mobile number.`,
+      );
+    }
+
+    if (seenPhones.has(phone)) {
+      throw new BadRequestException(
+        `Row ${rowNumber}: duplicate phone "${phone}".`,
+      );
+    }
+    seenPhones.add(phone);
+
+    rows.push({ rowNumber, phone, firstName, lastName });
+  });
+
+  if (rows.length === 0) {
+    throw new BadRequestException('Excel has no customer rows to import.');
+  }
+
+  if (rows.length > 10_000) {
+    throw new BadRequestException('Excel has too many rows (max 10,000).');
+  }
+
+  return rows;
+}
+
+export function customersExcelFilename(now = new Date()) {
+  const parts = new Intl.DateTimeFormat('en-GB', {
+    timeZone: 'Asia/Tehran',
+    year: 'numeric',
+    month: '2-digit',
+    day: '2-digit',
+    hour: '2-digit',
+    minute: '2-digit',
+    hourCycle: 'h23',
+  }).formatToParts(now);
+
+  const pick = (type: Intl.DateTimeFormatPartTypes) =>
+    parts.find((part) => part.type === type)?.value ?? '';
+
+  const date = `${pick('year')}-${pick('month')}-${pick('day')}`;
+  const time = `${pick('hour')}-${pick('minute')}`;
+  return `customers - ${date} - ${time}.xlsx`;
+}
+
+/** Normalize Iranian/local input to E.164 (e.g. +989121111111). */
+export function normalizeCellToE164(input: string): string | null {
+  const trimmed = input.trim();
+  if (!trimmed) return null;
+  if (E164_RE.test(trimmed)) return trimmed;
+
+  const digits = toLatinDigits(trimmed).replace(/\D/g, '');
+  if (!digits) return null;
+
+  if (digits.startsWith('98') && digits.length >= 12) {
+    const value = `+${digits}`;
+    return E164_RE.test(value) ? value : null;
+  }
+
+  if (digits.startsWith('0') && digits.length >= 11) {
+    const value = `+98${digits.slice(1)}`;
+    return E164_RE.test(value) ? value : null;
+  }
+
+  if (digits.length === 10 && digits.startsWith('9')) {
+    const value = `+98${digits}`;
+    return E164_RE.test(value) ? value : null;
+  }
+
+  if (/^[1-9]\d{6,14}$/.test(digits)) {
+    const value = `+${digits}`;
+    return E164_RE.test(value) ? value : null;
+  }
+
+  return null;
+}
+
+function writeInstructionColumns(sheet: ExcelJS.Worksheet) {
+  const faLines = [
+    'فقط ستون phone الزامی است.',
+    'نام و نام خانوادگی اختیاری‌اند (برای شخصی‌سازی پیامک).',
+    'رمز عبور لازم نیست — حساب‌های جدید با رمز تصادفی ساخته می‌شوند.',
+    'فرمت شماره: 0912… یا +98912…',
+    'شماره‌های تکراری در فایل یا مشتری‌های موجود نادیده گرفته می‌شوند.',
+    'این فایل برای افزودن مشتری جهت ارسال پیامک است.',
+  ];
+  const enLines = [
+    'Only the phone column is required.',
+    'first_name / last_name are optional (for SMS personalization).',
+    'No password column — new accounts get a random unusable password.',
+    'Phone format: 0912… or +98912…',
+    'Duplicates in the file or already-linked customers are skipped.',
+    'Use this file to add customers for SMS sending.',
+  ];
+
+  faLines.forEach((line, index) => {
+    const row = sheet.getRow(index + 2);
+    if (!row.height || row.height < 20) {
+      row.height = 20;
+    }
+
+    const faCell = row.getCell(5);
+    faCell.value = line;
+    faCell.font = { size: 11 };
+    faCell.alignment = { wrapText: true, vertical: 'top', readingOrder: 'rtl' };
+
+    const enCell = row.getCell(6);
+    enCell.value = enLines[index] ?? '';
+    enCell.font = { size: 11 };
+    enCell.alignment = { wrapText: true, vertical: 'top', readingOrder: 'ltr' };
+  });
+}
+
+/** Prefer local 09… display for Iranian numbers in the spreadsheet. */
+function formatPhoneForExcel(phone: string) {
+  if (phone.startsWith('+98') && phone.length === 13) {
+    return `0${phone.slice(3)}`;
+  }
+  return phone;
+}
+
+function looksPersian(value: string) {
+  return /[\u0600-\u06FF]/.test(value);
+}
+
+function readHeaderMap(sheet: ExcelJS.Worksheet): Partial<Record<HeaderKey, number>> {
+  const headerRow = sheet.getRow(1);
+  const map: Partial<Record<HeaderKey, number>> = {};
+
+  headerRow.eachCell((cell, colNumber) => {
+    const key = HEADER_ALIASES[normalizeHeader(cellText(cell.value))];
+    if (key && !map[key]) {
+      map[key] = colNumber;
+    }
+  });
+
+  return map;
+}
+
+function normalizeHeader(value: string) {
+  return value.trim().toLowerCase().replace(/\s+/g, ' ');
+}
+
+function optionalName(value: string): string | null {
+  const trimmed = value.trim();
+  return trimmed ? trimmed.slice(0, 100) : null;
+}
+
+function cellText(value: ExcelJS.CellValue): string {
+  if (value == null || value === '') return '';
+  if (typeof value === 'string' || typeof value === 'number' || typeof value === 'boolean') {
+    return String(value).trim();
+  }
+  if (value instanceof Date) return '';
+  if (typeof value === 'object' && 'text' in value && typeof value.text === 'string') {
+    return value.text.trim();
+  }
+  if (typeof value === 'object' && 'richText' in value && Array.isArray(value.richText)) {
+    return value.richText.map((part) => part.text).join('').trim();
+  }
+  if (typeof value === 'object' && 'result' in value) {
+    return cellText(value.result as ExcelJS.CellValue);
+  }
+  return String(value).trim();
+}
+
+function toLatinDigits(value: string) {
+  return [...value]
+    .map((char) => {
+      const persian = PERSIAN_DIGITS.indexOf(char);
+      if (persian >= 0) return String(persian);
+      const arabic = ARABIC_DIGITS.indexOf(char);
+      if (arabic >= 0) return String(arabic);
+      return char;
+    })
+    .join('');
+}
diff --git a/src/customers/customers.controller.ts b/src/customers/customers.controller.ts
index e84db56..4436a21 100644
--- a/src/customers/customers.controller.ts
+++ b/src/customers/customers.controller.ts
@@ -1,4 +1,5 @@
 import {
+  BadRequestException,
   Body,
   Controller,
   Delete,
@@ -7,8 +8,13 @@ import {
   Patch,
   Post,
   Query,
+  StreamableFile,
+  UploadedFile,
   UseGuards,
+  UseInterceptors,
 } from '@nestjs/common';
+import { FileInterceptor } from '@nestjs/platform-express';
+import { memoryStorage } from 'multer';
 import { AuthUser } from '../auth/auth.types';
 import { CurrentUser } from '../auth/decorators/current-user.decorator';
 import { RequireBusinessPermission } from '../auth/decorators/require-business-permission.decorator';
@@ -16,9 +22,12 @@ import { BusinessPermissionGuard } from '../auth/guards/business-permission.guar
 import { JwtAuthGuard } from '../auth/guards/jwt-auth.guard';
 import { DailyActivityQueryDto } from '../common/dto/daily-activity-query.dto';
 import { CustomersService } from './customers.service';
+import { customersExcelFilename } from './customers-excel';
 import { CreateCustomerDto } from './dto/create-customer.dto';
 import { ListCustomersDto } from './dto/list-customers.dto';
 import { SearchCustomersDto } from './dto/search-customers.dto';
+import { SendCustomerSmsDto } from './dto/send-customer-sms.dto';
+import { SendCustomersBulkSmsDto } from './dto/send-customers-bulk-sms.dto';
 import { UpdateCustomerDto } from './dto/update-customer.dto';
 
 @Controller('businesses/:businessId/customers')
@@ -56,6 +65,40 @@ export class CustomersController {
     return this.service.search(businessId, query, user);
   }
 
+  @Get('export')
+  @RequireBusinessPermission('orders.read')
+  async exportExcel(
+    @Param('businessId') businessId: string,
+    @CurrentUser() user: AuthUser,
+  ) {
+    const buffer = await this.service.exportExcel(businessId, user);
+    const filename = customersExcelFilename();
+    return new StreamableFile(buffer, {
+      type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+      disposition: `attachment; filename="${filename}"; filename*=UTF-8''${encodeURIComponent(filename)}`,
+      length: buffer.length,
+    });
+  }
+
+  @Post('import')
+  @RequireBusinessPermission('orders.create')
+  @UseInterceptors(
+    FileInterceptor('file', {
+      storage: memoryStorage(),
+      limits: { fileSize: 8 * 1024 * 1024 },
+    }),
+  )
+  importExcel(
+    @Param('businessId') businessId: string,
+    @UploadedFile() file: Express.Multer.File,
+    @CurrentUser() user: AuthUser,
+  ) {
+    if (!file) {
+      throw new BadRequestException('Excel file is required.');
+    }
+    return this.service.importExcel(businessId, file, user);
+  }
+
   @Post()
   @RequireBusinessPermission('orders.create')
   create(
@@ -66,6 +109,28 @@ export class CustomersController {
     return this.service.create(businessId, body, user);
   }
 
+  /** Bulk / quantity SMS via Gama SendBulk. Empty userIds → all enabled customers. */
+  @Post('sms')
+  @RequireBusinessPermission('orders.update')
+  sendBulkSms(
+    @Param('businessId') businessId: string,
+    @Body() body: SendCustomersBulkSmsDto,
+    @CurrentUser() user: AuthUser,
+  ) {
+    return this.service.sendBulkSms(businessId, body, user);
+  }
+
+  @Post(':userId/sms')
+  @RequireBusinessPermission('orders.update')
+  sendSms(
+    @Param('businessId') businessId: string,
+    @Param('userId') userId: string,
+    @Body() body: SendCustomerSmsDto,
+    @CurrentUser() user: AuthUser,
+  ) {
+    return this.service.sendSms(businessId, userId, body, user);
+  }
+
   @Patch(':userId')
   @RequireBusinessPermission('orders.update')
   update(
diff --git a/src/customers/customers.service.ts b/src/customers/customers.service.ts
index 487d702..1d4d724 100644
--- a/src/customers/customers.service.ts
+++ b/src/customers/customers.service.ts
@@ -1,16 +1,25 @@
-import { BadRequestException, ConflictException, ForbiddenException, Injectable, NotFoundException } from '@nestjs/common';
+import { BadRequestException, ConflictException, ForbiddenException, Injectable, NotFoundException, ServiceUnavailableException } from '@nestjs/common';
 import { Prisma } from '@prisma/client';
 import * as bcrypt from 'bcrypt';
+import { randomBytes } from 'crypto';
 import { AuthUser } from '../auth/auth.types';
 import { PermissionsService } from '../auth/permissions.service';
+import { SmsService } from '../auth/sms.service';
 import {
   buildDualDailyActivitySeries,
   startOfLocalDay,
 } from '../common/daily-activity';
+import { normalizeBusinessSettings } from '../business-settings/business-settings.util';
 import { PrismaService } from '../prisma/prisma.service';
+import {
+  buildCustomersExcel,
+  parseCustomersExcel,
+} from './customers-excel';
 import { CreateCustomerDto } from './dto/create-customer.dto';
 import { ListCustomersDto } from './dto/list-customers.dto';
 import { SearchCustomersDto } from './dto/search-customers.dto';
+import { SendCustomerSmsDto } from './dto/send-customer-sms.dto';
+import { SendCustomersBulkSmsDto } from './dto/send-customers-bulk-sms.dto';
 import { UpdateCustomerDto } from './dto/update-customer.dto';
 
 type CustomerListRow = {
@@ -33,6 +42,7 @@ export class CustomersService {
   constructor(
     private readonly prisma: PrismaService,
     private readonly permissions: PermissionsService,
+    private readonly sms: SmsService,
   ) {}
 
   async list(
@@ -231,6 +241,210 @@ export class CustomersService {
     };
   }
 
+  async exportExcel(businessIdRaw: string, actor: AuthUser) {
+    const businessId = BigInt(businessIdRaw);
+    await this.assertPermission(businessId, actor.id, 'orders.read');
+
+    const rows = await this.prisma.$queryRaw<
+      {
+        cellNumber: string;
+        firstName: string | null;
+        lastName: string | null;
+      }[]
+    >(Prisma.sql`
+      SELECT
+        u.cell_number AS "cellNumber",
+        u.first_name AS "firstName",
+        u.last_name AS "lastName"
+      FROM business_customers bc
+      JOIN users u ON u.id = bc.user_id
+      WHERE bc.business_id = ${businessId}
+      ORDER BY bc.created_at DESC, u.id DESC
+    `);
+
+    return buildCustomersExcel(
+      rows.map((row) => ({
+        phone: row.cellNumber,
+        firstName: row.firstName?.trim() ?? '',
+        lastName: row.lastName?.trim() ?? '',
+      })),
+    );
+  }
+
+  async importExcel(
+    businessIdRaw: string,
+    file: Express.Multer.File | undefined,
+    actor: AuthUser,
+  ) {
+    const businessId = BigInt(businessIdRaw);
+    await this.assertPermission(businessId, actor.id, 'orders.create');
+
+    if (!file?.buffer?.length) {
+      throw new BadRequestException('Excel file is required.');
+    }
+
+    const name = file.originalname?.toLowerCase() ?? '';
+    if (name && !name.endsWith('.xlsx')) {
+      throw new BadRequestException('Please upload an .xlsx Excel file.');
+    }
+
+    const business = await this.prisma.business.findUnique({
+      where: { id: businessId },
+    });
+    if (!business?.isActive) {
+      throw new NotFoundException('Business not found');
+    }
+
+    const customerRole = await this.prisma.role.findUnique({
+      where: { slug: 'customer' },
+    });
+    if (!customerRole) {
+      throw new Error('Customer role is missing. Run database migrations first.');
+    }
+
+    const rows = await parseCustomersExcel(file.buffer);
+    const phones = rows.map((row) => row.phone);
+
+    const existingUsers = await this.prisma.user.findMany({
+      where: { cellNumber: { in: phones } },
+      select: {
+        id: true,
+        cellNumber: true,
+        cellVerifiedAt: true,
+        businessCustomers: {
+          where: { businessId },
+          select: { id: true },
+        },
+      },
+    });
+    const userByPhone = new Map(
+      existingUsers.map((user) => [user.cellNumber, user]),
+    );
+
+    const existingUserIds = existingUsers.map((user) => user.id);
+    const staffMemberships =
+      existingUserIds.length === 0
+        ? []
+        : await this.prisma.businessUser.findMany({
+            where: {
+              businessId,
+              userId: { in: existingUserIds },
+            },
+            select: { userId: true },
+          });
+    const staffUserIds = new Set(
+      staffMemberships.map((row) => row.userId.toString()),
+    );
+
+    let created = 0;
+    let linked = 0;
+    let skipped = 0;
+    const skipSamples: string[] = [];
+
+    const noteSkip = (message: string) => {
+      skipped += 1;
+      if (skipSamples.length < 12) {
+        skipSamples.push(message);
+      }
+    };
+
+    const placeholderPasswordHash = await bcrypt.hash(
+      randomBytes(32).toString('hex'),
+      10,
+    );
+
+    for (const row of rows) {
+      const existing = userByPhone.get(row.phone);
+
+      if (existing?.businessCustomers.length) {
+        noteSkip(`Row ${row.rowNumber}: already a customer (${row.phone}).`);
+        continue;
+      }
+
+      if (existing && staffUserIds.has(existing.id.toString())) {
+        noteSkip(
+          `Row ${row.rowNumber}: user is staff of this business (${row.phone}).`,
+        );
+        continue;
+      }
+
+      const wasNew = !existing;
+
+      await this.prisma.$transaction(async (tx) => {
+        let userId = existing?.id;
+
+        if (!userId) {
+          const account = await tx.user.create({
+            data: {
+              cellNumber: row.phone,
+              passwordHash: placeholderPasswordHash,
+              firstName: row.firstName,
+              lastName: row.lastName,
+              cellVerifiedAt: new Date(),
+            },
+          });
+          userId = account.id;
+          userByPhone.set(row.phone, {
+            id: account.id,
+            cellNumber: row.phone,
+            cellVerifiedAt: account.cellVerifiedAt,
+            businessCustomers: [{ id: BigInt(0) }],
+          });
+        } else if (existing && !existing.cellVerifiedAt) {
+          await tx.user.update({
+            where: { id: userId },
+            data: { cellVerifiedAt: new Date() },
+          });
+        }
+
+        await tx.businessCustomer.create({
+          data: {
+            businessId,
+            userId,
+          },
+        });
+
+        const hasCustomerRole = await tx.userRole.findUnique({
+          where: {
+            userId_roleId: {
+              userId,
+              roleId: customerRole.id,
+            },
+          },
+        });
+
+        if (!hasCustomerRole) {
+          await tx.userRole.create({
+            data: {
+              userId,
+              roleId: customerRole.id,
+            },
+          });
+        }
+
+        const cached = userByPhone.get(row.phone);
+        if (cached && cached.businessCustomers.length === 0) {
+          cached.businessCustomers = [{ id: BigInt(0) }];
+        }
+      });
+
+      if (wasNew) {
+        created += 1;
+      } else {
+        linked += 1;
+      }
+    }
+
+    return {
+      message: 'Customers imported.',
+      total: rows.length,
+      created,
+      linked,
+      skipped,
+      skipSamples,
+    };
+  }
+
   async create(
     businessIdRaw: string,
     dto: CreateCustomerDto,
@@ -463,6 +677,156 @@ export class CustomersService {
     return { success: true };
   }
 
+  async sendSms(
+    businessIdRaw: string,
+    userIdRaw: string,
+    dto: SendCustomerSmsDto,
+    actor: AuthUser,
+  ) {
+    const businessId = BigInt(businessIdRaw);
+    const userId = BigInt(userIdRaw);
+    await this.assertPermission(businessId, actor.id, 'orders.update');
+
+    const membership = await this.prisma.businessCustomer.findUnique({
+      where: {
+        businessId_userId: { businessId, userId },
+      },
+      include: {
+        user: true,
+        business: { select: { settings: true, isActive: true } },
+      },
+    });
+
+    if (!membership || !membership.business.isActive) {
+      throw new NotFoundException('Customer not found for this business');
+    }
+
+    if (!this.sms.isEnabled()) {
+      return {
+        enabled: false,
+        message: 'SMS is disabled. Message was not sent.',
+      };
+    }
+
+    const settings = normalizeBusinessSettings(membership.business.settings);
+    const source =
+      settings.sms.senderNumber?.trim() || this.sms.getAdvertisingSource();
+
+    try {
+      const result = await this.sms.sendMessage(
+        membership.user.cellNumber,
+        dto.message.trim(),
+        { source },
+      );
+      return {
+        enabled: true,
+        message: 'Message sent successfully',
+        serverId: result.serverId,
+        source,
+      };
+    } catch (err) {
+      if (
+        err instanceof BadRequestException ||
+        err instanceof ServiceUnavailableException
+      ) {
+        throw err;
+      }
+      throw new ServiceUnavailableException('Unable to send SMS');
+    }
+  }
+
+  /**
+   * Bulk SMS (Gama SendBulk). Empty/omitted userIds → all enabled business customers.
+   * Selected userIds may include team members shown on the customers list.
+   */
+  async sendBulkSms(
+    businessIdRaw: string,
+    dto: SendCustomersBulkSmsDto,
+    actor: AuthUser,
+  ) {
+    const businessId = BigInt(businessIdRaw);
+    await this.assertPermission(businessId, actor.id, 'orders.update');
+
+    const business = await this.prisma.business.findUnique({
+      where: { id: businessId },
+      select: { settings: true, isActive: true },
+    });
+    if (!business?.isActive) {
+      throw new NotFoundException('Business not found');
+    }
+
+    const selectedIds = (dto.userIds ?? [])
+      .map((id) => id.trim())
+      .filter(Boolean);
+
+    let cellNumbers: string[];
+
+    if (selectedIds.length > 0) {
+      const userIds = selectedIds.map((id) => {
+        try {
+          return BigInt(id);
+        } catch {
+          throw new BadRequestException('Invalid user id');
+        }
+      });
+
+      const rows = await this.prisma.$queryRaw<{ cellNumber: string }[]>(Prisma.sql`
+        SELECT DISTINCT u.cell_number AS "cellNumber"
+        FROM users u
+        LEFT JOIN business_customers bc
+          ON bc.user_id = u.id AND bc.business_id = ${businessId}
+        LEFT JOIN business_users bu
+          ON bu.user_id = u.id AND bu.business_id = ${businessId}
+        WHERE u.id IN (${Prisma.join(userIds)})
+          AND (bc.id IS NOT NULL OR bu.id IS NOT NULL)
+      `);
+      cellNumbers = rows.map((r) => r.cellNumber);
+    } else {
+      const rows = await this.prisma.businessCustomer.findMany({
+        where: { businessId, isEnabled: true },
+        select: { user: { select: { cellNumber: true } } },
+      });
+      cellNumbers = rows.map((r) => r.user.cellNumber);
+    }
+
+    if (cellNumbers.length === 0) {
+      throw new BadRequestException('No recipients found to send SMS');
+    }
+
+    if (!this.sms.isEnabled()) {
+      return {
+        enabled: false,
+        message: 'SMS is disabled. Message was not sent.',
+        recipientCount: cellNumbers.length,
+      };
+    }
+
+    const settings = normalizeBusinessSettings(business.settings);
+    const source =
+      settings.sms.senderNumber?.trim() || this.sms.getAdvertisingSource();
+
+    try {
+      const result = await this.sms.sendBulkMessage(cellNumbers, dto.message.trim(), {
+        source,
+      });
+      return {
+        enabled: true,
+        message: 'Message sent successfully',
+        recipientCount: result.recipientCount,
+        serverIds: result.serverIds,
+        source,
+      };
+    } catch (err) {
+      if (
+        err instanceof BadRequestException ||
+        err instanceof ServiceUnavailableException
+      ) {
+        throw err;
+      }
+      throw new ServiceUnavailableException('Unable to send SMS');
+    }
+  }
+
   private formatLabel(user: {
     firstName: string | null;
     lastName: string | null;
diff --git a/src/customers/dto/send-customer-sms.dto.ts b/src/customers/dto/send-customer-sms.dto.ts
new file mode 100644
index 0000000..2f9f417
--- /dev/null
+++ b/src/customers/dto/send-customer-sms.dto.ts
@@ -0,0 +1,8 @@
+import { IsString, MaxLength, MinLength } from 'class-validator';
+
+export class SendCustomerSmsDto {
+  @IsString()
+  @MinLength(1)
+  @MaxLength(700)
+  message!: string;
+}
diff --git a/src/customers/dto/send-customers-bulk-sms.dto.ts b/src/customers/dto/send-customers-bulk-sms.dto.ts
new file mode 100644
index 0000000..eafd63b
--- /dev/null
+++ b/src/customers/dto/send-customers-bulk-sms.dto.ts
@@ -0,0 +1,27 @@
+import { Type } from 'class-transformer';
+import {
+  ArrayMaxSize,
+  IsArray,
+  IsOptional,
+  IsString,
+  MaxLength,
+  MinLength,
+} from 'class-validator';
+
+export class SendCustomersBulkSmsDto {
+  @IsString()
+  @MinLength(1)
+  @MaxLength(700)
+  message!: string;
+
+  /**
+   * When omitted or empty → send to all enabled business customers.
+   * When provided → only those user ids that belong to this business.
+   */
+  @IsOptional()
+  @IsArray()
+  @ArrayMaxSize(5000)
+  @IsString({ each: true })
+  @Type(() => String)
+  userIds?: string[];
+}
diff --git a/src/public-sms/dto/send-public-sms.dto.ts b/src/public-sms/dto/send-public-sms.dto.ts
index ba978fc..91646ab 100644
--- a/src/public-sms/dto/send-public-sms.dto.ts
+++ b/src/public-sms/dto/send-public-sms.dto.ts
@@ -1,4 +1,4 @@
-import { IsNotEmpty, IsString, MaxLength, MinLength } from 'class-validator';
+import { IsNotEmpty, IsOptional, IsString, Matches, MaxLength, MinLength } from 'class-validator';
 
 export class SendPublicSmsDto {
   @IsString()
@@ -16,4 +16,12 @@ export class SendPublicSmsDto {
   @MinLength(1)
   @MaxLength(700)
   message!: string;
+
+  /** Optional Gama shortcode override (digits only). */
+  @IsOptional()
+  @IsString()
+  @Matches(/^\d{8,16}$/, {
+    message: 'source must be an 8–16 digit shortcode',
+  })
+  source?: string;
 }
diff --git a/src/public-sms/public-sms.service.ts b/src/public-sms/public-sms.service.ts
index 1645bb4..3d291ab 100644
--- a/src/public-sms/public-sms.service.ts
+++ b/src/public-sms/public-sms.service.ts
@@ -34,7 +34,9 @@ export class PublicSmsService {
 
     await this.assertRateLimits(partnerDomain, msisdn);
 
-    const result = await this.sms.sendMessage(msisdn, dto.message);
+    const result = await this.sms.sendMessage(msisdn, dto.message, {
+      source: dto.source?.trim() || undefined,
+    });
     this.logger.log(
       `Partner SMS accepted domain=${partnerDomain} serverId=${result.serverId}`,
     );