[VoiceOps] Calls coming up as spam on mobile carriers

Jay Hennigan jay at west.net
Fri Jul 8 14:43:30 EDT 2022

On 7/8/22 10:00, Shawn L wrote:
> We're having a strange one at $dayjob.  When one of our customers (in 
> this case a hospital) calls a patient back on a cell phone, the calls 
> are coming up with SPAM? in the caller id.  It seems to be happening 
> with both Verizon and AT&T.

Many things can trigger this. Does the hospital use this ANI for batches 
of automated calls such as billing and/or appointment reminders? 
Algorithms detecting large numbers of calls in batches can trigger it. 
I've personally received a reverse-911 call marked as "Spam Risk" by AT&T.

> We've checked the the DIDs in question have and are sending the proper 
> caller id, checked the Neustar database, etc. and can't find anything 
> that's missing.  These are TDM calls.  They come in over multiple TDM 
> PRIs and leave toward an AT&T tandem on a legacy TDM trunk group, so 
> there's really no way to do STIR/SHAKEN call attesting.

It's the terminating cellular carrier marking it based on their own 
proprietary algorithms. Typically the call goes through as normal with 
CNAM changed to "Spam Risk" or similar.

> Our switch vendor (Ribbon / Genband / Nortel)  also mentioned that 
> they've had other clients with the issue and it seems to be limited to 
> calls placed to mobile carriers.  Another telco was able to find an AT&T 
> portal to register the numbers as legitimate, but it only lasted for 
> about a month before they had to do it again.
> I haven't researched where at AT&T they might have entered the numbers, 
> but that doesn't seem like a valid option for a hospital with a thousand 
> numbers.

Is the hospital placing calls originating from all of those thousand 
numbers, or just from one?

> Just wondering if others have seen this, and if anyone knows of a way to 
> resolve it.

Don't use the same originating number for both bulk automated calls, 
particularly collection calls, and individual callbacks originated by a 

Expect bulk automated calls to be marked as spam, even if they are 
legitimate appointment reminders, etc. If you place such calls, program 
your dialer to detect a voicemail greeting/beep and leave voicemail if 
possible. In most cases the calls will delivered and the only thing 
changed is the CNAM display.

It may be that a bad actor is spoofing your number for spam calls and 
you're getting listed that way. Spammers spoofing a hospital may result 
in a higher answer rate as people are more likely to pick up thinking 
that a friend or relative may have been injured.

Encourage those expecting such calls to add the hospital number to the 
contact list on their phone.

Also, if any of your customers are in the business of selling extended 
car warranties, lose those customers. /s

Jay Hennigan - jay at west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV

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