As topic says, was working, now it's not. Jailbroken 3.1.2 with pwnage on 4.26.08 modem- Funny thing is, my wifes mms stopped working about 2 weeks prior. Everything else is okay and I've even tried to contact att to fix along with network reset. No luck-
I've had similar problems with 2 iPhones in our family plan. They seem to send to each other, as well as anyone on AT&T with the iPhone but if I send to anyone on other networks or other phones, its hit and miss. Super annoying really.