In Mexico, with Mexican Sim, calling a Mexican phone

[metaphoricink]

I have an unlocked HTC Incredible 2, Verizon version, purchased in the U.S. And not from Verizon -- so I have no customer service recourse there.

I live in Mexico, and have bought and used Sim cards for Mexico service from Telcel. The phone receives calls just fine. It sends and receives texts just fine.

BUT when I try to call a number in Mexico the phone thinks it is trying to call the U.S. so tries area codes there. I cannot complete "local" mexican calls.

I can't for the life of me find a setting for base country. I've turned off assisted dialing, but that didn't help.

I'm not visiting here, I'm living here. Can someone please help me figure out how to tell the phone that when I'm in Mexico and I'm dialing a Mexican number using a Mexican carrier, that I'd like to call Mexico?

Thanks!