Sorry to hear that!
In order to access data services, your phone must be compatible with our network with the right set of frequency bands. Additionally you must add APN settings on your device before you start using US Mobile (The exact configuration depends on your device).
If you have any problems feel free to contact our Customer Support team, which is available 24/7 to help troubleshoot any issues you may have. Contact us at firstname.lastname@example.org, by dialing 611 on your US Mobile phone, or chatting via the chat box. We are here to help!