u s cellular text msg to/from mexican cell phone us

On a blackberry curve 8330, using US Cellular, I can send a text message to a cell phone in Mexico that uses Telcel for their service. But that same phone in Mexico cannot send me back a message. With the Verizon network in the US (& the same Telcel network in Mexico), we were able to communicate both ways, back and forth.

I have read and looked and searched...does anyone have any ideas why this won't work and how it could be fixed?

Thanks,

you need to call cs and have them to add international text messaging to your account.