Last March, I took an unlocked cellphone to Telcel and got a chip and 30 day prepaid contract for $160 pesos ($9 US). It included unlimited calls in Mexico and the US, Twitter, Facebook, Whatsapp, some photo sharing program I don't use and some megabytes that were mostly used up immediately with updates. I didn't need the MBs and didn't buy more, as I was mostly in CDMX where free WiFi is everywhere. I could have uploaded the aps via WiFi but wasn't yet up to speed. Whatsapp is a must nowadays for communication with escorts and one I hadn't met before had me send her a phone photo of my room key before she would come to me. Lots of escorts on Twitter and Facebook too, so it is almost as though the deal was structured for visiting mongers.