I have verizon and have not had problems in the past here in Aca. I have sms and imessage working fine. Wifi is fine. No cell data and no phone service. I usually get a text upon arrival about caution while roaming and prices. I have the mexico data plan in place just no service.
Wife has ATT and is having no issues. This would be why we have two plans but it is irritating. Both phones worked fine in Cabo at Xmas but not now. Bummer