[cisco-voip] SCCP/SDL trace question re:transfer

[Ed Leatherman]

Hi Sreekanth,

The problem is inconsistent, but definitely more than say 20%. Load on our
systems doesn't appear to be an issue, we did testing late at night/after
hours and regular call volume is very low then. We were able to duplicate
the issue just with cell phones as the target, so it seems the problem is
not just the answering service not picking up; not had a problem where
direct calls weren't answered promptly.

In looking through the trace files, it seems like Unity does a consult
transfer even when set to "Release to switch", its just sending the 2nd
transfer command as soon as the initial call setup starts - IIRC it was
doing it right after we got "PROCEEDING" from PSTN.

I did check out the T301 timer in CUCM but its still set to 3 minutes - so
we're not hitting that one at least.

Your idea of reproducing the issue with a consultative transfer from a
phone is a good one, we'll give that a try.

For now we just have their line directly forwarded after hours manually and
skipping Unity completely and it works. They pay per call to the answering
service though so they really want the front end IVR to pick up first. It
is a suicide prevention hotline and they are very sensitive to us throwing
solutions at it until something works - I'll have to at least pin down the
part that is failing before they will accept a workaround. I have a mini
UCCX script setup to do a call redirect to the number, if I can verify that
it is the consultative transfer that is the issue I plan on just sending
the call from Unity to UCCX and letting UCCX get the call offsite - will
probably just move the whole call tree to UCCX for IVR at that point.


Thanks for your ideas!!

Ed


On Mon, Sep 1, 2014 at 3:04 AM, Sreekanth Narayanan <sknth.n at gmail.com>
wrote:

> Hi Ed,
>
> Could it be possible that the answering service does not answer the call
> sometimes? This may be causing the timeout.
> From the POV of the CUCM, this is just another regular outgoing call over
> PRI starting from a VM port (which acts like an SCCP phone), which would
> then do the transfer to the initial caller.
> The transfer type in your case seems to be semi-attended or consult
> transfer and not blind. I don't know if this can be changed on Unity.
>
> What is the frequency of this issue? In 10 calls transferred this way, how
> many times do you see it?
> Maybe you could try a couple of different tests here to try and isolate
> the issue:
> 1. Make direct calls from an IP phone (sccp preferably) to the answering
> service and see if the answering service picks the call up every time
> without fail.
> 2. Make an inbound call to the CUCM from PSTN, and direct this call to an
> sccp phone (this is replacing the Unity), and then do a blind, consult
> transfer (2 different tests) to the answering service and see if you can
> reproduce the problem.
>
> Thanks
> Sreekanth
>
>
> On 1 September 2014 00:28, Ed Leatherman <ealeatherman at gmail.com> wrote:
>
>> Hello!
>>
>> I'm trying to help chase down a intermittent issue where Unity needs to
>> transfer a caller off-site to an answering service, and sometimes the
>> transfer doesn't complete and the caller gets left on-hold. I was hoping
>> someone could explain a message i'm seeing in the traces during a failure.
>>
>> SCCP integration to unity connection. 9.1 software versions on both CUCM
>> and Unity. MGCP to PRI gateways. All gateways are set to offnet and service
>> parameter is configured to allow transfers between offnet to rule that out
>> as a issue.
>>
>> On the trace side of things, for the transfer leg on a failure I see:
>> 19:55:27.146 : Unity "presses transfer" , dials out the digits
>> 19:55:29.853 : Q931 IN from PSTN for the transfer leg,  PROGRESS message
>> 19:55:29.855 : CUCM OUT to Unity: Call State Ring out
>> *19:55:41.020 : CUCM OUT to Unity: DisplayNotify timeOutValue=15
>> notify='Cannot Complete Transfer' content='Cannot Complete Transfer' ver=12*
>>
>> It looks like an abnormal amount of time for the call to connect, is that
>> a possible reason for the "Cannot Complete Transfer" message? Is the
>> timeout tweakable someplace?
>>
>>  On successful tries, the transfer leg connects faster (less than 10
>> seconds). So far we haven't found anything else different on our own; have
>> a TAC case open on it but getting shuffled between groups now (unity team
>> wants CUCM team to look at it).
>>
>> Unity never seems to retrieve the caller from hold or try again,
>> eventually the caller hangs up (I see the the DISCONNECT message from PSTN)
>> at which point that call leg gets torn down.
>>
>> Any ideas much appreciated
>>
>> Ed
>>
>>
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>>
>>
>


-- 
Ed Leatherman
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