[VoiceOps] SIP return message on misdials - 487 or 500/503 or ?

[Calvin Ellison]

+1 on Glen's answer.

Intermediate carriers deal with enough FAS and other garbage that they
cannot trust every 404 or 604. We've determined that it's better to 503 a
possibly invalid number for the customer to later retry, than falsely 404 a
valid number and get complaints about how we trashed their expensive number
list. So long as there is no pre-session media before the 404/604 (i.e.
180/183 tri-tone, voice reject, busy, etc.), we and/or the customer can
still route advance and potentially connect that call.



Regards,

*Calvin Ellison*
Voice Services Engineer
calvin.ellison at voxox.com
+1 (213) 285-0555

-----------------------------------------------
*voxox.com <http://www.voxox.com/> *
9276 Scranton Rd, Suite 200
San Diego, CA 92121
[image: Voxox]

On Mon, Oct 12, 2015 at 12:11 PM, Glen Gerhard <ggerhard at sansay.com> wrote:

> Hi Erick,
>
> the only carrier who knows the number is invalid is the LEC/CLEC that owns
> the block.  They probably will send back a 404 Not Found or 604 in most
> cases.  However unless you are directly connected to them you may not get
> that response returned to you.  The intermediate carriers will generally be
> configured to return a 503 in case of any failure.
>
> Also the Cancels you see may be due to the termination carrier playing an
> inband ring media that is a tri-tone "your call cannot be completed as
> dialed" message.  Since it is during the ring phase the caller (or dialer
> app) will Cancel the call resulting in a 487 cause code.  For dialer apps
> this is a benefit since the good ones will recognize the tri-tone and
> remove the number from their calling list.
>
> ~Glen
>
>
> On 10/5/2015 9:19 AM, Erick Bergquist wrote:
>
> Thanks for the replies.
>
> On the cause 41 I get a 503 which matches up.
>
> Getting cause 63 back for the ones where I see SIP 500 Internal Server
> Failure which is default behavior.
>
>  I guess I'm good then, just wish I wouldn't see 5xx level for
> mis-dials. Yes, the numbers are valid E164 formatted numbers for US
> which the provider wants to see in that format.   I can't call these
> numbers from other sytems either so they are indeed bad, un-allocated
> numbers.
>
>
> Thanks, Erick
>
> On Mon, Oct 5, 2015 at 10:51 AM, Jay Hennigan <jay at west.net> <jay at west.net> wrote:
>
> On 10/5/15 8:16 AM, Erick Bergquist wrote:
>
> Hello,
>
> Just trying to get idea of what is normal on what providers should
> return for a misdial, bad unknown number, etc.
>
> On one provider, I get a CANCEL and a 487 Request Terminated on mis-dials.
>
> On another provider, I get a 503 Service Unavailable and a 500
> Internal Service Error back.
>
>
> It depends. CANCEL and 487 Request Terminated typically comes from the
> originator and means that you hung up before the call completed. Carrier was
> in post-dial delay and hadn't returned anything (yet).
>
> 503 means that the carrier can't or won't process the call. Could be a
> misdial where the number can't be parsed as in not enough or too many
> digits, prefix starts with 1 or 0, etc. Could also be that you tried to dial
> a valid number that the carrier doesn't handle, such as international,
> 900/976, etc. Could also mean that you didn't pay your bill or are coming
> from an IP address that isn't a customer of that carrier.
>
> For a number that is in the correct format but isn't in service, you might
> see 503 or also 404 or 604.
>
> 500 internal service error is usually a technical problem with the carrier
> and not a misdial.
>
> Different carriers map ISDN/SS7 cause codes to SIP differently. See:
> https://www.google.com/search?q=isdn+cause+code+to+sip+mapping
>
> --
> 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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