Why might my Sprint cellphone usually be unable to receive calls from AT&T cellphones?

May 8, 2012 3:49 PM

Why might my Sprint cellphone usually be unable to receive calls from AT&T cellphones?

I've had support tickets open with both companies, but they've resulted in more frustration than progress. I wonder if someone who knows more about how these things work can give me some keywords to mention to the techs.

I can make calls to the problematic AT&T phones, and send and receive texts, and even receive calls on rare occasions, but usually attempts to call me are met with either dead air or the tri-tone beep and "your call cannot be completed as dialed". Service seems to be completely normal w/r/t every other carrier, though I haven't searched exhaustively.

This has happened since I got the phone about a month ago. I didn't port the phone number over from another carrier, and a week ago I had them change the number just in case that would sort something out.

AT&T suggested that I ask Sprint to verify and rebroadcast my local routing number. The person I talked to at Sprint surmised that they were talking about rebroadcasting my home location register. Those don't seem like equivalent things judging by the wiki, but I don't know. Should I try again to get someone to do the local routing number thing? Does it make any sense to request a replacement SIM card? I'm not sure if it could be implicated or if that's just completely outside the domain of its functionality. Is there anything else I can ask?

posted by moift to Technology (6 answers total)

Best answer: at&t is definitely sending the calls to the wrong place somehow. I would expect that for a ported number, but not so much if it's in one of Sprint's blocks. Have an at&t customer put in a trouble ticket stating that calls to xxx-xxx-xxxx fail. There is nothing anyone they can talk to at the call center can do to fix this. It's not an account provisioning problem, it's a routing problem. Eventually someone will act on it and, if necessary, some engineer from at&t will call some engineer over at Sprint and get it worked out.

I'm mildly surprised that someone at&t told you to ask Sprint to do something rather than dealing with it directly.
posted by wierdo at 5:08 PM on May 8, 2012 [1 favorite]

Best answer: Actually, rereading your description, I think there's one or more bad voice trunks between at&t and Sprint, and not a routing problem. Do you know anyone with an at&t phone from a different market than whereever the phones having trouble are from? If so, I suspect they would not have the same trouble calling you.
posted by wierdo at 5:18 PM on May 8, 2012 [1 favorite]

Response by poster: wierdo, thanks so much for the leads. I only know of AT&T cells from two different places, and both have problems. It seems as though one may be slightly different in nature in that they report getting a long silence, whereas people from the other region report the "call cannot be completed" message. It's possible everyone gets a mixture of both behaviors, though, as I don't have detailed accounts.
posted by moift at 7:11 PM on May 8, 2012

There used to be error codes on those messages, specifically for figuring out where the problem lies. "You call cannot be completed, code 2MD." Etc. Have you (or your callers) written down that number?
posted by gjc at 7:40 PM on May 8, 2012 [1 favorite]

Not sure if this is relevant or not...

I have ATT, friend has Verizon. We have different state area codes. For about 4 years, I had his number in my address book without a 1 on the front. One day, out of the blue, my calls would not go through to him, same as you described. I tried dialing 1+ the number and it works again.
posted by thatguyjeff at 7:16 AM on May 9, 2012 [1 favorite]

Response by poster: It appears wierdo was exactly right, and it got sorted out somehow from the AT&T end. Thanks a lot!
posted by moift at 1:01 PM on June 18, 2012