1. How does SIM swap work?

Step 1: Customer approach 

Pretending to be a network operator to support customers: 

Swap to 4G-5G SIM

  • Notice that the SIM has a problem that needs to be fixed/replaced  
    Convince customers by: 
  • Accurately know customer's personal information such as Full name, identity number, date of birth, address…


Step 2: Take control of customer’s mobile SIM

2 main tricks

  • **21*phone number# press OK Call forwarding: redirect or forward incoming calls to criminal’s mobile number, including auto calls to provide Voice OTP 
  • DS* send 901 (* is SIM Seri number)  Disable SIM: SIM is invalidated and transferred to criminal's SIM 



Step 3: Account take over

  • Criminals bypass multi-factor authentication mechanisms to access the victim’s accounts and perform account takeover through: receive an OTP via SMS or a call to the registered mobile number



2. How to protect your online banking customers from SIM Swap fraud 


Should perform the SIM conversion/upgrade directly at the telecom stores

Use SIM PIN to enhance security 

  • Android: 

Step 1: Settings > Select Biometrics and security > Select More security settings..

Step 2: Set up a SIM card lock, and you start setting up a 4- to 8-digit PIN code

  • IOS: 

Settings> Select Cellular > Select SIM PIN> Turn on SIM PIN, you enter PIN to lock the SIM


Absolutely NOT type the syntax **21*phone number# or DS* according to unknown request

Absolutely NOT provide sensitive information such as identification number, activation /OTP authentication code, CVV, PIN, card number to anyone, through any contact channel.

Absolutely NOT share personal information ( phone number, email, bank account number…) on social media



    What you should do when you suspect Sim Swap fraud


3. What you should do when you suspect Sim Swap fraud:

  • Immediately contact the network operator to block the phone number (including blocking messages, calls to the phone number).
  • Lock online payment features, lock bank cards to avoid fraudsters trying to steal information.
  • Contact directly to Techcombank for timely support to lock e-banking accounts:: 
    • Techcombank's nationwide branches
    • Customer Service Center (hotline 24/7): 1800588822 (domestic) or (+84) 2439446699 (international)
    • Email: call_center@techcombank.com.vn


In addition, we recommend that you report to the nearest police station or follow the instructions in the "Instructions on denunciation of crimes" section of the Ministry of Public Security's website (https://bocongan.gov.vn or https://mps.gov.vn