HTC U11 ATT and Telcel compatibility in Mexico

[Sterling147]

I currently have an HTC U11 on the Sprint network. I am now living in Mexico and Sprint has given me a service providing me with free unlimited calling, texting to the U.S., and Canada as well as unlimited high speed data. I am looking into switching to a Mexican carrier, either TelCel or ATT, when my contract expires or phone is paid off. Does anybody know whether the U11 will be compatible with ATT or TelCel in Mexico after I have Sprint unlock it? Thank you for your help.