Three times within the last week I have been told by three different callers that they tried to call me and got a message saying the number they have dialed is not a working number. I have a full signal and my phone is working fine because I have received other calls and after the ones who got the message tried over and over it finally went through. I have had the same number with AT&T since 1997 without any such problems. I have never had my number disconnected because of a late payment or anything like that.
I'm experiencing the identical problem. I could have written your post.
To add: I contacted ATT and they had some info about towers in my area being worked on. I explained that the problem was not only in one location in the city but multiple (Austin, TX) so that probably wasn't it. They confirmed that all of my iphone 4 OS updates were current and had me reset my phone. They pushed something my way. Nothing has changed and may actually be worse. I have done this twice now. They are supposed to call me tomorrow afternoon to check in. My phone is a company phone so I know the bill is current and also no one else in the company is having the same problem. Usually I'm the lucky one!
I had this happen to me but it was the other way around--I was trying to call out and it kept saying "that number is not a working number." I was calling a Verizon #. I then called my work phone (sprint) and it worked. I figured that meant there was a problem on the other person's side, but I was able to call the Verizon # from my Sprint phone. So it was either my fault or some sort of mutual problem between AT&T and Verizon.
I am in Austin also. When I called AT&T the tech said there was nothing wrong on AT&T's end but a friend of his had recently called him from a Sprint phone and got the same message so it must be a problem with Sprint. I asked one of the aforementioned who had called me if they had Sprint service and he said no he has AT&T so that tech was full of crap.
Originally, I thought it was only my phone in the company having the problem and the previous 3 weeks of calls to ATT revolved around that anomaly. On Tuesday (my 3rd? conversation) ATT tech support said that it could be a bad SIM card or device and I should go to the ATT store and request a new SIM (free of charge as noted on the account call-in records). If that didn't work, do a "restore" on my phone. Lastly, contact Apple for a new device. During that conversation, she cleared my network settings. No one had done that before but it worked as well as everything else.
Originally, I thought it was only my phone in the company having the problem and the previous 3 weeks of calls to ATT revolved around that anomaly. Come to find out that 2 other phones on our account are having similar issues. Yesterday (Friday) I called to inform ATT of such and they admitted that it seems more like a network problem. The tech said that the routing numbers for the phones affected were not correct whatever that means. She corrected the routing numbers and is to call me today to see if there have been any other episodes. We'll see . . .
One important thing. They have to have two verifiable occurrences of failed calls either in or out. I only could say for sure that I called #XX at 1:02PM and got the message. If you could give them the exact phone # and time of the problem, they can fill out a ticket. Whatever. Just passing along what I know.
It could have been VZ or at&t that had something wrong and the LRN was pointing to the wrong place. It is a very easy fix if you can get CC to get a ticket opened with the right group. Having both the calling and dialed numbers with time is very helpful.
Basically with local number portability any number can be with any carrier. So when you dial a number it does a DB lookup and returns the LRN for the switch your number is located in. If that gets messed up it sends you to the wrong place. It could have been either at&t or VZ that had the issue but like I said...it is an easy fix if you get it to the right group.
I hope that the LRN thing clears up the problem. We'll see. My only question would be the randomness of the problem -- maybe 5-10% of the time? Wouldn't it be more consistent if the network was sending calls to me or from me via the wrong route? Also, we haven't ported a number into our account for years, so I don't know how this just came up.
Oh well, I only want the problem corrected and the details of an explanation would be lost on me anyway.