[VoiceOps] Terminating 800 traffic with Caller ID of an 800 #

Jay Hennigan jay at west.net
Wed Feb 15 22:17:50 EST 2012

On 2/15/12 3:29 PM, Darren Schreiber wrote:
> Hi folks,
> We have a customer who is insisting on setting their outbound Caller ID
> to an 800 #. They are complaining that /they /can't call other 800 #s.
> Our testing reveals that many carriers are refusing to route the call
> when the Caller ID is set as an 800 #.

There's a reason for that.  Many carriers also refuse to route email
when the sender claims to be wealthy royalty from Nigeria.

If you are a legitimate  operation, calling with a TF number as your
CLID raises the same red flags as sending email in all caps claiming to
be wealthy royalty from Nigeria.

They can't call my friend's house, either, without jumping through a
hoop.  99% of those calling with a TF caller-ID, 000-000-0000 or
anything else not matching the NANP are rogue telemarketing scum who
call despite the target number being on the do-not-call list.  The other
1% are people like your customer that think it's a good thing to claim
to be originating calls from a DID that by definition isn't supposed to
originate calls and don't mind raising red flags.  I think he also
directs calls with CNAM matching the name of any US state similarly.

Here's how he handles it.  Asterisk does a challenge-response.  It
answers the phone, says "hello", pauses two seconds to fool the
answering-machine-detect of predictive dialers, then plays a recording
instructing these callers, if human and not a telemarketer, to hang up
and call back within five minutes and enter a 4-digit number generated
at random and read to them (which stays valid for five minutes).  Humans
behind telemarketing dialers may not even know what number they have
dialed and don't often have the ability to call back anyway.  Legitimate
persons calling from a business which has CLID (stupidly, IMHO) set to a
TF number generally do know and can call back.

If they pass the challenge, it rings the phone.  If not, subsequent
calls go here...


There are a few TF numbers in his whitelist that have passed the
challenge, his stockbroker, for example.

Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
Impulse Internet Service  -  http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV

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