Can I use my phone while in Mexico? Are there roaming charges?
there is no international service or coverage so no extra cost from Republic
the phone will work on open WiFi to make calls and text back to the US
a US base calling card or third party apps (think Google Voice or Skype) can be used to make “local” calls via WiFi
also if it’s a 3.0 phone you an swap the SIM to a local one.