CUCM alerting while call is busy

[Oleh Doroshenko]

Hi all.

Yesterday i faced with problem:

Ringing tone is generated to IpPhone1(from CUCM i guess) while call declined by customer.

Design

IpPhone---CUCM---SIPtrunk---Redundant Voice gateways---E1 PRI --- PSTN---Customer Phone

On the voice gateway:

debug isdn q931

i see message  "Busy received" and channel is cleaned.

But even after channel clearing IPphone keep receiving ringing tone for about 30 sec.

If call is answered - no problems. Normal clearing and call termination.

If no channels available or all ports are shutdown no rerouting via redundant gateway occur.

I guess Voice gateway do not send some important message or waits for some event but i cant firure up for what. Maybe i missed something important in config.

Configuration of Voice GW is appended.

Any help is greatly appreciated.

[Ayodeji Okanlawon]

Oleg,

This is not the first time I have see this. It seem to be common to sip trunks...

Can you do a test call and send the ff:

debug isdn q931

debug ccsip messages

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[Oleh Doroshenko]

Appended this debugs.

Where xxxxxxx - calling number, yyyyyyy - called number.

Call from Ipphone to pstn user.

I see from ccsip log - voice GW DO NOT SEND any message after user busy reseived. Only SESSION PROGRESS instead of BYE or CANCEL.

[Ayodeji Okanlawon]

Can you please enable the debigs together. I need to correlate isdn logs to sip logs...

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[Oleh Doroshenko]

Here are concatenated debug.

[Carlo Poggiarelli · Accepted solution]

Hi oleg.

add voice call disc-pi-off to your config.

HTH

Regards

Carlo

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"The more you help the more you learn"

[Ayodeji Okanlawon · Accepted solution]

From the logs,

When the Telco sends a disconnect, it sends a PI (progress indicator-perhaps plays a prompt rather that the usual disconnect), hence as far as the gateway is concerend the call is still in progress and therefore does not send a disconnect to cucm

Oct 25 09:00:00.042: ISDN Se0/0/0:15 Q931: RX <- DISCONNECT pd = 8  callref = 0x80A1

        Cause i = 0x8491 - User busy

        Progress Ind i = 0x8288 - In-band info or appropriate now available

*Oct 25 09:00:00.042: ISDN Se0/0/0:15 Q931: call_disc: PI received in disconnect; Postpone sending RELEASE for callid 0x8041

Detailed explanation of this is below:

The debug Isdn q931 command output shows this message when the Public Switched Telephone Network (PSTN) user hangs up the call:

ISDN Se1/0:15 Q931: call_disc: PI received in disconnect; Postpone sending RELEASE for callid 0x8012

Resolution

Issue the voice call disc-pi-off command on the gateway so the gateway treats a disconnect message with a Progress Indicator (PI), as it treats a standard disconnect without a PI, (issue the voice call disc-pi-off command in global configuration mode).

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[Ayodeji Okanlawon]

+5 Carlo. Keep the good work going.

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[Carlo Poggiarelli]

..and +5 to Aok for always giving excellent and detailed answers.

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"The more you help the more you learn"

[Oleh Doroshenko]

TY guys. Now busy calls are threated correctly.