[VoiceOps] SIP 404 Not Found vs 603 Decline

Jay Hennigan jay at west.net
Wed Jun 3 12:44:44 EDT 2015

On 6/2/15 1:58 PM, Peter Beckman wrote:
> I offer a feature to our customers that allows them to configure their DID
> to respond with "This number is disconnected" message for specific,
> annoying callers, based on their CallerID.
> Some customers send a Busy signal (486 BUSY) for these annoying callers. It
> seems that some Robocallers will retry numbers that ring busy repeatedly,
> sometimes annoyingly aggressively.
> I'm switching the default to declining the call, which brings me to which
> SIP response is correct and/or ideal.

486 Busy has the advantage that it usually won't route-advance, ending 
the churn on the network for that call. Letting the abusers churn and 
waste their resources retrying forever may not be a bad thing.

200 OK followed by a "Go away" intercept recording[1] would be another 
option. Let the call supervise and cost the abusers a fraction of a cent 
without bothering any humans on the receiving end.

You don't want to do this if the endpoint is a tollfree number, obviously.

[1] Asterisk's "Our phone system has been eaten by monkeys" might be a 
good choice.

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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