My wife is from Ensenada, Baja California originally, but lived in Tijuana before we got married. I bought her a gophone back when GoPhone still had the $1 unlimited m2m plan. The nice thing was that she lived in a part of TJ that still got AT&T signal. So most of the time no roaming. The great thing was when we went past the border (like down to Ensenada, or Mexico City, or Culiacan (Sinaloa), it was only .25/min to keep in touch with the US.
We still have the same phone number with gophone and we've had it now activated for 4.5 years now. Never let us down.
* 2012: Samsung GS3, Nokia 2720
* 2010: BB 8350i, Nokia 2720
* 2009: Mot i9, BB7520
* 2008: HTC Tilt, Mot i450
* 2007: SE W810i, Samsung A707, HTC 8125, Samsung BlackJack
* 2006: Mot L6, SE Z520, Nokia 6682
* 2005: Kyo 7135, Sam i600, Mot V551, Nokia 6230, 6620, SE Z600
* 2004: Motorola V300, SE T610, Kyo 6035, Nokia 3390
* 2003: Motorola T720C
* 2002: Audiovox CDM4000, 9000, 9155GPX, Thera