Ideal would be a dual sim unlocked GSM quad band phone
Reality any relatively new (past 4 years) unlocked GSM quad band should work well.
T Mobile offers an international plan, some have reported data slower than using a local carrier's SIM.
We use local SIM, Skype call, and hotspot feature.
SPOT a good Device to alert family
members where you are and OK, also a handy backup EPIRB
function. Cost ~120, 100/year subscription.
Delorme Inreach next option, similar to spot but allows limited texting and recently OCENS Marine weather
download. Cost ~$300 and monthly subscription varies between $30-$80/month.