Some Vietnamese network operators, primarily Mobifone, occasionally block BTM SMS. If you are unable to receive the verification SMS within a couple of minutes, you have a number of alternatives:

1. Use a foreign non-Vietnamese number
2. Use another Vietnamese (not Mobifone) number
3. Use another BitcoinVN ATM (BTM5 and above) that does not require a mobile number at all
4. Contact the number shown on the BTM. We will use our company’s SIM card in order to provide the verification code to you