Lumia 925 Group Text Issue

Hi all,

I'm just wondering if anyone else has had this issue. My mom recently got the Lumia 925 on AT&T, and when she receives text messages to a group, it puts them in a new thread with her number included. So for example, she sends a text to a group with person 1 and person 2. If someone responds, the response ends up in a separate thread with person 1, person 2 and her #.

Unsurprisingly the people at AT&T had no clue, so I'll have to try Nokia next, but I figured I'd try here first.

Any ideas?