diff --git a/prisma/migrations/20260808140000_sms_auto_block_below/migration.sql b/prisma/migrations/20260808140000_sms_auto_block_below/migration.sql
new file mode 100644
index 0000000..6a52480
--- /dev/null
+++ b/prisma/migrations/20260808140000_sms_auto_block_below/migration.sql
@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE `sms_accounts` ADD COLUMN `auto_block_below_rials` INTEGER NULL;
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index db1596b..1be2c23 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -89,6 +89,8 @@ model SmsAccount {
   balanceRials        Int      @default(0) @map("balance_rials")
   pricePerPartRials   Int      @default(2500) @map("price_per_part_rials")
   isBlocked           Boolean  @default(false) @map("is_blocked")
+  /// If set: block non-alert SMS when balanceRials < this. Null = only manual isBlocked.
+  autoBlockBelowRials Int?     @map("auto_block_below_rials")
   /// below this => red/critical
   alertCriticalRials  Int      @default(10000) @map("alert_critical_rials")
   /// at/below this (and above critical) => yellow; above => green
diff --git a/src/sms/dto/sms-account.dto.ts b/src/sms/dto/sms-account.dto.ts
index bb23125..33bdefa 100644
--- a/src/sms/dto/sms-account.dto.ts
+++ b/src/sms/dto/sms-account.dto.ts
@@ -6,6 +6,7 @@ import {
   IsString,
   Max,
   Min,
+  ValidateIf,
 } from 'class-validator';
 import { Type, Transform } from 'class-transformer';
 
@@ -19,6 +20,18 @@ export class UpdateSmsAccountDto {
   @IsBoolean()
   isBlocked?: boolean;
 
+  /** Null clears auto-block; omit leaves unchanged. UI sends tomans×10 as rials. */
+  @IsOptional()
+  @Transform(({ value }) => {
+    if (value === null || value === '' || value === undefined) return value === undefined ? undefined : null;
+    const n = Number(value);
+    return Number.isFinite(n) ? Math.trunc(n) : value;
+  })
+  @ValidateIf((_, v) => v !== null && v !== undefined)
+  @IsInt()
+  @Min(0)
+  autoBlockBelowRials?: number | null;
+
   @IsOptional()
   @IsInt()
   @Min(0)
diff --git a/src/sms/sms.service.ts b/src/sms/sms.service.ts
index 97d1059..da8250a 100644
--- a/src/sms/sms.service.ts
+++ b/src/sms/sms.service.ts
@@ -146,6 +146,10 @@ export class SmsService {
       data: {
         pricePerPartRials: dto.pricePerPartRials ?? undefined,
         isBlocked: dto.isBlocked ?? undefined,
+        autoBlockBelowRials:
+          dto.autoBlockBelowRials === undefined
+            ? undefined
+            : dto.autoBlockBelowRials,
         alertCriticalRials: dto.alertCriticalRials ?? undefined,
         alertWarningRials: dto.alertWarningRials ?? undefined,
         gatewayProvider: dto.gatewayProvider ?? undefined,
@@ -254,21 +258,25 @@ export class SmsService {
     let reason: string | null = null;
     let allowed = true;
 
-    // Only the explicit block switch stops sending (parity with Hamkar/Khanegi panels).
-    // Negative / low balance is allowed; UI can still show balanceLevel as warning.
+    // Manual block switch, then optional auto-block threshold (empty = no auto block).
+    // Alert SMS (isAlert) always bypasses both. Negative balance alone does not block.
     if (account.isBlocked && !isAlert) {
       allowed = false;
       reason = 'blocked';
+    } else if (this.isAutoBlocked(account) && !isAlert) {
+      allowed = false;
+      reason = 'auto_blocked';
     } else if (!isAlert && account.balanceRials < estimatedCostRials) {
       reason = 'insufficient_balance';
     }
 
     return {
       allowed,
-      blocked: account.isBlocked,
+      blocked: account.isBlocked || this.isAutoBlocked(account),
       reason,
       balanceRials: account.balanceRials,
       pricePerPartRials: account.pricePerPartRials,
+      autoBlockBelowRials: account.autoBlockBelowRials,
       parts: safeParts,
       estimatedCostRials,
       balanceLevel,
@@ -303,9 +311,16 @@ export class SmsService {
         });
       }
 
+      if (this.isAutoBlocked(account) && !isAlert) {
+        throw new ForbiddenException({
+          message: 'ارسال پیامک به‌خاطر کمتر بودن موجودی از آستانه خودکار مسدود است',
+          reason: 'auto_blocked',
+        });
+      }
+
       const costRials = parts * account.pricePerPartRials;
 
-      // Allow negative wallet (same as product panels): only isBlocked stops send/consume.
+      // Negative wallet still allowed unless manual/auto block applies.
       const nextBalance = account.balanceRials - costRials;
 
       const updated = await tx.smsAccount.update({
@@ -869,6 +884,16 @@ export class SmsService {
     return `${new Intl.NumberFormat('fa-IR').format(toman)} تومان`;
   }
 
+  private isAutoBlocked(account: {
+    balanceRials: number;
+    autoBlockBelowRials: number | null;
+  }) {
+    return (
+      account.autoBlockBelowRials != null &&
+      account.balanceRials < account.autoBlockBelowRials
+    );
+  }
+
   private chargeInfoOf(account: SmsAccount) {
     return {
       card: account.chargeCard || '',
@@ -884,6 +909,7 @@ export class SmsService {
       balanceRials: account.balanceRials,
       pricePerPartRials: account.pricePerPartRials,
       isBlocked: account.isBlocked,
+      autoBlockBelowRials: account.autoBlockBelowRials,
       alertCriticalRials: account.alertCriticalRials,
       alertWarningRials: account.alertWarningRials,
       chargeCard: account.chargeCard,