To receive the code, you will need to apply using a US cell phone number that is backed by one of the major US wireless service providers. You will not be able to apply while using a VPN, with a VoIP number, or with any virtual phone numbers. You must currently be within the 50 states of the US to receive the code.
If you have a T-Mobile phone number, or if your phone blocks specific numbers, please be sure to contact your carrier directly to allow our code to come through.