Losing GSM network when traveling to a new city.

[Rami5]

Phone:
Model: Sprint Touch Pro 2
Network: Unlocked to work with AT&T.
ROM: Running MightyROM

Problem:
Currently when I stay in the same city the phone works wonderful. It stays on the GSM network. As soon as I travel to a different city, I lose the GSM signal and the phone switches back to CDMA. Then the phone switches to CDMA only and wont let me choose GSM. Sometimes it says no SIM card is detected.

Solutions:
Some things I have to do to get it working is go to the Comm Manager and turn the phone radio OFF then back ON. The phone picks up the GSM network then it switches to CDMA again. Sometimes I have to do a soft reset. Other times I have to take out the battery. take the SIM card out and put it back in.

Anyone know how to prevent this from happening? Thank you.