Redundant E1 PRI. Fail establishing voice payload.

[Oleh Doroshenko]

Hi all.

We have 2 CISCO3925-V/K9 equipped with PVDM3 64-channel to 128-channel factory upgrade and

VWIC3-2MFT-T1/E1 cards. IOS 15.1(4)M

Architecture:

Call flow:

When call flows via E1 PRI 1 and E1 PRI 2 call succeeds both in and out ISP to 6921.

When call hits E1 PRI 3:

Outbound call(both E1 PRI 1 and E1 PRI 2 are shut down):

Debug isdn q931:

*May 10 11:32:02.602: ISDN Se0/0/1:15 Q931: TX -> DISCONNECT pd = 8  callref
= 0x807F
        Cause i = 0x80A2 - No circuit/channel available*May 10 11:32:02.790: ISDN Se0/0/1:15 Q931: RX <- RELEASE pd = 8  callref =
0x007F
*May 10 11:32:02.802: ISDN Se0/0/1:15 Q931: TX -> RELEASE_COMP pd = 8
callref = 0x807F

I hear dial-tone from ISP and then get disconnect

Inbound call: Phone begin ringing but caller already hears - announcement from ISP - "call cannot be established, abonent is offline...".

If call is answered by phone, gateway connects E1 channel but do not notice call already failed - so there no voice traffic.

ISP said - it is problem with my GW and "Redundancy scheme configured wrong"

I try to figure out if it my prolem or not. And if mine where to look to? Transcoding seems ok, codecs too. E1s was configured standalone but i changed scheme to trunkgroup.

Any suggestions appreiated. TY for help

[Suresh Subramanian]

can you please post your configuration and 'debug isdn q931' for failed call?

inbound is working on E1-PRI 3?

please post the result of 'show trunk group' command

[Aman Soi]

Hi,

Please provide the architecture diagram as well .

Is third E1 PRI  connected on second router? also, are u using MGCP or H.323.

Lastly, is this problem only for 6921 phones or for other IP phone models as well.

regds,

aman

[Oleh Doroshenko]

No, H.323 or MGCP is not used. Only SIP trunk between CUCM and 3925. No all phones affected.

Architecture in attachment

Everything workink fine on phone - to CUCM. The problem somewhere ISP - 3925, transcoding, trunks, because only E1 PRI 3 affected. About incoming and outgoing call - look to original pots. Config and debug will be later.

[Ayodeji Okanlawon]

It is certainly a problem with your gateway. From the trace:

May 10 11:32:02.602: ISDN Se0/0/1:15 Q931: TX -> DISCONNECT pd = 8  callref

= 0x807F

Your gateway is disconnecting the call when this particular E1 is used.

Please send your sh run and the output of "show voice dsp voice

"

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[Oleh Doroshenko]

Hi again. Attached some files - show run, debug isdn q931 - for incoming and outgoing call, sh trunk group.

Also made some experiment -- switched physical connection of E1 PRI 2 and E1 PRI 3. And now the E1 PRI 2 expiriencing same problems and   E1 PRI 3 working fine. I called telco but they still saying its not their problem

Also checked mistakes acording to

Understanding debug isdn q931 Disconnect Cause Codes

( http://www.cisco.com/en/US/tech/tk801/tk379/technologies_tech_note09186a008012e95f.shtml )

PS: forget to say - L1 and L2 ISDN working fine(status - ACTIVE, an Multiple_frame_established) and also

[Ayodeji Okanlawon · Accepted solution]

From these logs, your provider are disconnecting the call saying there is no B channel to make the call. You need to send these logs to them. Th log you sent previously showed your gateway disconnecting the call. This time the disconnct is coming from their end. The inbound call logs is not properly attached because I cant access them. Can you attach them? Can you also send the output of show voice dsp voice

               Exclusive, Channel 1

Jun 13 12:38:43.046: ISDN Se0/0/0:15 Q931: RX <- CALL_PROC pd = 8  callref = 0x8084

        Channel ID i = 0xA98381

                Exclusive, Channel 1

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

Jun 13 12:38:53.046: ISDN Se0/0/0:15 Q931: RX <- DISCONNECT pd = 8  callref = 0x8084

        Cause i = 0x82A2 - No circuit/channel available

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[Oleh Doroshenko]

After couple hour troubleshooting problem was solved.

It was telco's problem, you right. thank you for your time and help