It seems all of the major mobile phone carriers in the United States offer mobile instant messaging services (such as AIM, ICQ, MSN, Yahoo!, etc.), but I have not yet found a phone that supports T9 text input on these mobile IM applications. I've played around with a few Sprint and Verizon phones, and they all use some sort of web-based application to communicate on IM which does not allow you to use T9. It can be quite painful if you use mobile IM a lot and only have a numeric keypad on your phone.

I haven't had the privilige of playing with T-Mobile phones and never thought to try out mobile IM on the Cingular phones I've had my hands on, so maybe some of them support T9 with mobile IM....

Anyways, is this a carrier-specific thing or are there phones out there that allow T9 text input with instant messaging?