If you will pay roaming fees while in TJ depends on both who your carrier is and even more important what plan you have with your carrier.
I have a T-Mobile plan that eliminates roaming fees between the US and Mexico and have yet to find a place in northern Baja that it doesn't work. (Since I live in Tijuana I've used it in more places than you can shake a stick at.)
In Mexico, Telcel is the largest carrier, but I have a Movistar phone. They have a contract plan that for 200 pesos a month provides users with unlimited calls and texts without roaming fees plus a little 4G LTE data (which I don't need as I get data in TJ via my T-Mobile phone). I don't recommend contract plans for casual tourists, but Movistar offers good prepaid plans without roaming fees that will meet the needs of most tourists. (Telcel changes its plans at the drop of a hat, so sometimes they have no roaming fees and other times they do.)
Q: Why do I have a Movistar phone if my T-Mobile works everywhere?
A: Because many of my Mexican friends don't have free roaming and won't pay the fees needed to call a US number. Plus I like to get border crossing information from Telnor and Telnor blocks US numbers. (So I have an Sony Xperia dual sim phone and I am glad I do.)
FYI: You can get an old fashioned talk and text phone for either Telcel or Mexico usually for under US $30.00. You buy either in tons of places but there is both a Telcel and Movistar store on 5th between Revolucion and Consitution.
There is Telcel (Mexico) and Telcel USA. Last month I saw a Telcel USA plan that for US $30.00 a month provides unlimited talk and text without roaming fees plus 1 GB 4G LTE data on either side of the border. If you're looking for a "secret phone," a burner, etc. you might look at Telcel USA offerings.
-- Modified on 2/13/2017 12:56:34 AM