No US service

[Roland1]

Bought a US package a couple of weeks ago and when I got down to the states I had no service to call

[Sansan]

Are you still there? You need a VoLTE enabled phone. If possible, put your phone to 4G/LTE and connect to T-Mobile or AT&T.   

If calls still don't work, put your phone to 2G and connect to T-Mobile. From the settings menu, turn on data roaming.

[pmbc]

Does the addon show up on your account?  Did you connect to T-mobile or AT&T for service?