diff --git a/.env.example b/.env.example
index 7edc6d9..1575ba6 100644
--- a/.env.example
+++ b/.env.example
@@ -60,6 +60,7 @@ SMS_PROVIDER =
 SMS_API_KEY =
 AUTH_SMS_TEMPLATE =
 EXP_OTP_TIME =
+FAKE_OTP =
 
 # ---------------------------------------------
 # ⚙️  Application Features / Flags
diff --git a/src/auth/auth-services/user.auth.service.ts b/src/auth/auth-services/user.auth.service.ts
index 3555f6f..3d1ba7f 100644
--- a/src/auth/auth-services/user.auth.service.ts
+++ b/src/auth/auth-services/user.auth.service.ts
@@ -13,6 +13,8 @@ import {
 } from "src/helpers/iran-mobile";
 import {
   computeOtpExpireMs,
+  FAKE_OTP_CODE,
+  isFakeOtpEnabled,
   isOtpExpiryActive,
   readOtpExpireMinutesFromEnv,
 } from "src/helpers/user-otp-expiry";
@@ -109,7 +111,7 @@ export class UserAuthService {
     const userExist = await this.userDbService.findOne(
       buildUserLookupByPhone(canonicalMobile),
     );
-    const otp = this.otpCreator.create();
+    const otp = this.createOtpForRequest();
     const hashOtp = await this.hashService.hash(otp);
     const expireMinutes = readOtpExpireMinutesFromEnv();
     const nowMs = Date.now();
@@ -158,7 +160,23 @@ export class UserAuthService {
     return new LoginDtoRs(userExist);
   }
 
+  private createOtpForRequest(): string {
+    if (isFakeOtpEnabled()) {
+      this.logger.warn(
+        "FAKE_OTP=true — using fixed dev OTP; SMS provider is not called",
+      );
+      return FAKE_OTP_CODE;
+    }
+    return this.otpCreator.create();
+  }
+
   private async smsSender(otp: string, mobile: string) {
+    if (isFakeOtpEnabled()) {
+      this.logger.log(
+        `FAKE_OTP=true — skipped SMS for phone=${mobile} (use OTP ${FAKE_OTP_CODE})`,
+      );
+      return;
+    }
     const ok = await this.smsOrchestrationService.sendAuthOtp(
       mobile,
       otp,
diff --git a/src/helpers/user-otp-expiry.ts b/src/helpers/user-otp-expiry.ts
index 43c5f03..85352bd 100644
--- a/src/helpers/user-otp-expiry.ts
+++ b/src/helpers/user-otp-expiry.ts
@@ -41,3 +41,10 @@ export function readOtpExpireMinutesFromEnv(): number {
   const raw = Number(process.env.EXP_OTP_TIME ?? "2");
   return Number.isFinite(raw) && raw > 0 ? raw : 2;
 }
+
+/** Dev-only: skip SMS provider and accept a fixed OTP for any mobile. */
+export const FAKE_OTP_CODE = "12345";
+
+export function isFakeOtpEnabled(): boolean {
+  return process.env.FAKE_OTP === "true";
+}