diff --git a/src/api/integrations/channel/whatsapp/whatsapp.baileys.service.ts b/src/api/integrations/channel/whatsapp/whatsapp.baileys.service.ts
index 22839fd451..428d0362c5 100644
--- a/src/api/integrations/channel/whatsapp/whatsapp.baileys.service.ts
+++ b/src/api/integrations/channel/whatsapp/whatsapp.baileys.service.ts
@@ -4114,7 +4114,18 @@ export class BaileysStartupService extends ChannelStartupService {
           numberVerified = verify.find((v) => v.jid === user.jid);
         }
 
-        const numberJid = numberVerified?.jid || user.jid;
+        let numberJid = numberVerified?.jid || user.jid;
+        if (
+          user.number.startsWith('55') &&
+          user.number.length === 13 &&
+          user.number[4] === '9' &&
+          numberJid.includes('@s.whatsapp.net')
+        ) {
+          const jidNum = numberJid.split('@')[0];
+          if (jidNum.length === 12) {
+            numberJid = `${user.number}@s.whatsapp.net`;
+          }
+        }
 
         return new OnWhatsAppDto(
           numberJid,
diff --git a/src/api/services/channel.service.ts b/src/api/services/channel.service.ts
index 3ba03d5a02..a413452bf2 100644
--- a/src/api/services/channel.service.ts
+++ b/src/api/services/channel.service.ts
@@ -13,7 +13,7 @@ import { Auth, Chatwoot, ConfigService, Database, HttpServer, Proxy } from '@con
 import { Logger } from '@config/logger.config';
 import { NotFoundException } from '@exceptions';
 import { Contact, Message, Prisma } from '@prisma/client';
-import { createJid } from '@utils/createJid';
+import { createJid, formatBRNumber } from '@utils/createJid';
 import { WASocket } from 'baileys';
 import { isArray } from 'class-validator';
 import EventEmitter2 from 'eventemitter2';
@@ -478,23 +478,8 @@ export class ChannelStartupService {
     return jid;
   }
 
-  // Check if the number is br
-  public formatBRNumber(jid: string) {
-    const regexp = new RegExp(/^(\d{2})(\d{2})\d{1}(\d{8})$/);
-    if (regexp.test(jid)) {
-      const match = regexp.exec(jid);
-      if (match && match[1] === '55') {
-        const joker = Number.parseInt(match[3][0]);
-        const ddd = Number.parseInt(match[2]);
-        if (joker < 7 || ddd < 31) {
-          return match[0];
-        }
-        return match[1] + match[2] + match[3];
-      }
-      return jid;
-    } else {
-      return jid;
-    }
+  public formatBRNumber(jid: string): string {
+    return formatBRNumber(jid);
   }
 
   public async fetchContacts(query: Query<Contact>) {
diff --git a/src/utils/createJid.ts b/src/utils/createJid.ts
index 23a3afe1fa..0a3924ce46 100644
--- a/src/utils/createJid.ts
+++ b/src/utils/createJid.ts
@@ -13,23 +13,36 @@ function formatMXOrARNumber(jid: string): string {
   return jid;
 }
 
-// Check if the number is br
-function formatBRNumber(jid: string) {
-  const regexp = new RegExp(/^(\d{2})(\d{2})\d{1}(\d{8})$/);
-  if (regexp.test(jid)) {
-    const match = regexp.exec(jid);
-    if (match && match[1] === '55') {
-      const joker = Number.parseInt(match[3][0]);
-      const ddd = Number.parseInt(match[2]);
-      if (joker < 7 || ddd < 31) {
-        return match[0];
-      }
-      return match[1] + match[2] + match[3];
-    }
+const BRAZIL_COUNTRY_CODE = '55';
+const BRAZIL_PHONE_WITH_NINTH_DIGIT_LENGTH = 13;
+const BRAZIL_PHONE_WITHOUT_NINTH_DIGIT_LENGTH = 12;
+const BRAZIL_MOBILE_NINTH_DIGIT = '9';
+const COUNTRY_AND_AREA_CODE_LENGTH = 4;
+const FIRST_SUBSCRIBER_DIGIT_INDEX = 4;
+const MINIMUM_MOBILE_FIRST_DIGIT = 6;
+
+export function formatBRNumber(jid: string): string {
+  if (!jid.startsWith(BRAZIL_COUNTRY_CODE)) {
     return jid;
-  } else {
+  }
+
+  if (jid.length === BRAZIL_PHONE_WITH_NINTH_DIGIT_LENGTH) {
     return jid;
   }
+
+  if (jid.length === BRAZIL_PHONE_WITHOUT_NINTH_DIGIT_LENGTH) {
+    const firstSubscriberDigit = Number.parseInt(jid[FIRST_SUBSCRIBER_DIGIT_INDEX]);
+    const isMobileMissingNinthDigit = firstSubscriberDigit >= MINIMUM_MOBILE_FIRST_DIGIT;
+
+    if (isMobileMissingNinthDigit) {
+      const countryAndAreaCode = jid.slice(0, COUNTRY_AND_AREA_CODE_LENGTH);
+      const subscriberNumber = jid.slice(COUNTRY_AND_AREA_CODE_LENGTH);
+
+      return `${countryAndAreaCode}${BRAZIL_MOBILE_NINTH_DIGIT}${subscriberNumber}`;
+    }
+  }
+
+  return jid;
 }
 
 export function createJid(number: string): string {
diff --git a/src/utils/onWhatsappCache.ts b/src/utils/onWhatsappCache.ts
index 8d7a2c16a7..05233d6ebf 100644
--- a/src/utils/onWhatsappCache.ts
+++ b/src/utils/onWhatsappCache.ts
@@ -22,12 +22,24 @@ function getAvailableNumbers(remoteJid: string) {
 
   // Brazilian numbers
   if (remoteJid.startsWith('55')) {
-    const numberWithDigit =
-      number.slice(4, 5) === '9' && number.length === 13 ? number : `${number.slice(0, 4)}9${number.slice(4)}`;
-    const numberWithoutDigit = number.length === 12 ? number : number.slice(0, 4) + number.slice(5);
+    let numberWithDigit = number;
+    let numberWithoutDigit = number;
+
+    if (number.length === 13 && number.slice(4, 5) === '9') {
+      numberWithDigit = number;
+      numberWithoutDigit = `${number.slice(0, 4)}${number.slice(5)}`;
+    } else if (number.length === 12) {
+      const firstDigit = Number.parseInt(number.slice(4, 5));
+      if (firstDigit >= 6) {
+        numberWithDigit = `${number.slice(0, 4)}9${number.slice(4)}`;
+        numberWithoutDigit = number;
+      }
+    }
 
     numbersAvailable.push(numberWithDigit);
-    numbersAvailable.push(numberWithoutDigit);
+    if (numberWithoutDigit !== numberWithDigit) {
+      numbersAvailable.push(numberWithoutDigit);
+    }
   }
 
   // Mexican/Argentina numbers
@@ -48,7 +60,9 @@ function getAvailableNumbers(remoteJid: string) {
     const numberWithoutDigit = number.length === 12 ? number : number.slice(0, 2) + number.slice(3);
 
     numbersAvailable.push(numberWithDigit);
-    numbersAvailable.push(numberWithoutDigit);
+    if (numberWithoutDigit !== numberWithDigit) {
+      numbersAvailable.push(numberWithoutDigit);
+    }
   }
 
   // Other countries
@@ -129,8 +143,23 @@ export async function saveOnWhatsappCache(data: ISaveOnWhatsappCacheParams[]) {
       const newJidOptionsString = sortedJidOptions.join(',');
       const newLid = item.lid === 'lid' || item.remoteJid?.includes('@lid') ? 'lid' : null;
 
+      let targetRemoteJid = remoteJid;
+      if (existingRecord?.remoteJid) {
+        const existingNum = existingRecord.remoteJid.split('@')[0];
+        const newNum = remoteJid.split('@')[0];
+        if (
+          existingNum.startsWith('55') &&
+          existingNum.length === 13 &&
+          existingNum[4] === '9' &&
+          newNum.startsWith('55') &&
+          newNum.length === 12
+        ) {
+          targetRemoteJid = existingRecord.remoteJid;
+        }
+      }
+
       const dataPayload = {
-        remoteJid: remoteJid,
+        remoteJid: targetRemoteJid,
         jidOptions: newJidOptionsString,
         lid: newLid,
       };