AT&T's blue network SMS<->SMTP off the air

John Todd jtodd at
Thu Jun 17 06:26:30 UTC 2010

To those of you who may rely upon AT&T to deliver your email-to-SMS  
messages for monitoring: some of you may be currently out of luck.  I  
would just send this to the "outages at" list, but it  
does seem to be a meta-network failure in that for better or worse  
many of us use SMS as a method to monitor outages, so this perhaps  
moves it up a notch in the importance hierarchy enough to warrant a  
NANOG post.

I am experiencing failures on my email transmissions to my older  
"blue" (aka: Cingular) AT&T devices at the moment, for both incoming  
and outgoing.  Many of you may be using older "blue" cards in your NOC  
phones, SMS gateway devices, or perhaps even your personal mobile  
devices for those of you who still live in the dark ages of phones  
that aren't [2.5,3,4,x]G capable.

I am unable to diagnose the problems fully, but at least some (if not  
all) of the SMS-to-email gateway failures are due to's MX  
hosts (in the "" zone) being unreachable due to absence of  
functioning authoritative resolvers for that zone, and possibly other  
failures as well.  This appears to be causing "550 Access Denied"  
messages being returned to my mobile devices that are sending to email  
addresses, and mail spooling on my Internet SMTP hosts that are trying  
to send to the "NPAxxxyyyy at" addresses for SMTP-to-SMS relay.

There is a rumor that this is NOT related to the deactivation of the  
"downloads" components of the blue network on the 15th, but I suspect  
that someone just decided to pull the plug on everything.  Reading to  
the end of the thread below, there is someone who states AT&T claims  
it will be back online by the evening of the 17th at the surprisingly  
accurate time of 9:55 PM (timezone unstated.)

More speculation:

I don't know if this is causing problems with anyone using TAP  
interfaces, or with any of AT&T's other SMTP<->SMS gateway services  
like  SMS, and mobile devices in general, are a single  
point of failure for contacting on-call staff for various problems -  
perhaps it's time to insist that everyone carries two mobile devices,  
on different frequency and technology platforms, with different  
carriers, and split messages to both due to the anecdotally increasing  
failure rates of mobile networks.  Conspiracy theories of how  
collusive unreliability would increase ARPU across the board for all  
carriers would be interesting to hear... but not in this forum, I  
suspect.  :-)


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