I think it depends on the provider , I believe once I had done 1-52- (Mexico country code is 52) then the phone number. If that doesn’t work try 052 then the number or just 52 , I have had to mess around a few different ways . Also many Mexicans use WhatsApp app and it works like the phone , same phone number . I hope this helps!
How do I text to a Mexico phone from my American phone while in PP? Thank you!
Almost everyone in Mexico with a smart phone uses whatsapp so that is the best way when possible. But for a regular text message the easiest way to guarantee the correct dialing while roaming is to ignore the 1, 01, 001 etc and just use +52 and then the number, i.e. +52-638-123-4567. On iphone if you hold the "0" down you can access the "+" symbol, not sure how it works on android phones.