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.
* 2014: Sam Galaxy Avant, SE Z600
* 2012: Sam GS3, Nok 2720
* 2010: BB 8350i, Nok 2720
* 2009: Mot i9, BB7520
* 2008: HTC Tilt, Mot i450
* 2007: SE W810i, Sam A707, HTC 8125, Sam BlackJack
* 2006: Mot L6, SE Z520, Nok 6682
* 2005: Kyo 7135, Sam i600, Mot V551, Nok 6230, 6620, SE Z600
* 2004: Mot V300, SE T610, Kyo 6035, Nok 3390
* 2003: Mot T720C
* 2002: Audiovox CDM4000, 9000, 9155GPX, Thera