Using a US T-Mobile number from China

Voice and SMS on our T-Mobile plans run over Wi-Fi Calling, so a stable Wi-Fi path with UDP is the whole game.

What to do

1. Keep Wi-Fi Calling enabled on the T-Mobile line and stay on Wi-Fi — calls and texts travel over that data connection.
2. Pair it with a travel data eSIM: the data eSIM provides internet, the T-Mobile line keeps your US number reachable.
3. Use a UDP-capable VPN if your network needs one — the carrier tunnel does not survive a UDP-blocking proxy.
4. Turn off data roaming on the T-Mobile line if you only need voice and SMS, so it does not burn credit.
5. The line is for US numbers; international dialling is not a supported path. If calls fail while data works, recheck the Wi-Fi Calling steps.

Related articles