This problem began for us in December of 2004. They refused to open a trouble ticket. I was finally able to get them to open one in August. Every few weeks, when a customer is told my number isn't working, or when I have to make three and four calls to reach my partner (with identical Cingular service). Same deal for me. The techs won't talk to the public, and the customer service reps take the position that they don't know anything about it and they've never heard of such a problem. I put a voice mail message on my phone, explaining it, and I often am left messages that begin, "I'm also on cingular, and I have the same problem." Perhaps Cingular ought to do some web searching, because the above post pops right up as the first of many hits with a search of the form: cingular "not a working number"