1. A simple and cost effective way to phone home in
2. Another method to phone home is via skype in one of the many internet cafes. I am hghly virus skeptical about internet cafes aka 'cyber'. Bring a live CD like SLAX to get around that. Many computers are equipped with webcam and microphone.
3. Some cities, like San Luis, offer city wide free WIFI (article). Were you to bring a netbook, you would be set.
4. Many people do not use a long distance plan with their home phone. Instead they purchase a LD phone card at any corner kiosk.
5. The GSM network is well established. Although I have not tried it, you could also purchase a local SIM. (note: oddly you are required to declare/register your cellphone when you enter