I didn't know where best to post this since I don't know if it is a network, software, or device problem, so I'm putting it in all three. Sorry for the triplication!

I have family members who are traveling in California (I'm in Texas), and we wanted to stay in contact by SMS to avoid voice roaming charges. Since Thursday, 3/17/05, I've been getting the following error message when I try to SMS them: ''The network is not responding now, or the message center number is invalid''.

I called Cingular tech support and they checked my device over the air, including sending me a test message which I received just fine. They told me it was a device problem?

Has anyone had a similar problem? Any help would really be appreciated.