GSM roaming in Alberta

I found my GSM/GPRS roaming experience while in Alberta to be a little flakey. My ATTWS phone roamed onto Rogers and I had problems getting missed call notifications, vmail notifications. The T-mobile users in the family roamed onto another service (? MTS) and service was even flakier. If we did this regularly I guess the ATT/Rogers solution would be the best but I would look harder for better solutions.