diff --git a/src/users/users.service.ts b/src/users/users.service.ts
index c27d41a..17ca5fa 100644
--- a/src/users/users.service.ts
+++ b/src/users/users.service.ts
@@ -1,4 +1,8 @@
-import { Injectable, NotFoundException } from '@nestjs/common';
+import {
+  ConflictException,
+  Injectable,
+  NotFoundException,
+} from '@nestjs/common';
 import { InjectRepository } from '@nestjs/typeorm';
 import { Repository } from 'typeorm';
 import { CreateUserDto } from './dto/create-user.dto';
@@ -12,7 +16,8 @@ export class UsersService {
     private readonly usersRepository: Repository<User>,
   ) {}
 
-  create(createUserDto: CreateUserDto): Promise<User> {
+  async create(createUserDto: CreateUserDto): Promise<User> {
+    await this.ensureMobileIsUnique(createUserDto.mobile);
     const user = this.usersRepository.create(createUserDto);
     return this.usersRepository.save(user);
   }
@@ -31,6 +36,9 @@ export class UsersService {
 
   async update(id: string, updateUserDto: UpdateUserDto): Promise<User> {
     const user = await this.findOne(id);
+    if (updateUserDto.mobile) {
+      await this.ensureMobileIsUnique(updateUserDto.mobile, id);
+    }
     Object.assign(user, updateUserDto);
     return this.usersRepository.save(user);
   }
@@ -39,4 +47,14 @@ export class UsersService {
     const user = await this.findOne(id);
     await this.usersRepository.remove(user);
   }
+
+  private async ensureMobileIsUnique(
+    mobile: string,
+    excludeUserId?: string,
+  ): Promise<void> {
+    const existing = await this.usersRepository.findOneBy({ mobile });
+    if (existing && existing.id !== excludeUserId) {
+      throw new ConflictException('Mobile number already exists');
+    }
+  }
 }