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Inbound PSTN calls disconnect

Unanswered Question
Jan 31st, 2014
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Hello all,

A customer of ours keeps losing incoming PSTN calls. The phone rings but when they answer the call is disconnected. The site in question has 4 PSTN lines that connect into a voice gateway with 4 fxo ports. The gateway receives the call over the PSTN and then hands the last 4 digits up to the CUCM. The CUCM then translates these digits into a hunt group number for the site.

On the voice gateway we are seeing the debug output below when we run debug voice call trap. Does anyone know what this means. There is nothing on the forums or on the internet that I can see?

Jan 31 17:08:51.790 GMT: Potential Mute Call:  ---------------------------------------->what is this?

Jan 31 17:08:51.790 GMT: CallID1=3637; CallID2=3638; ConfID=1784

Jan 31 17:08:51.790 GMT: Leg 1: CallID=3637; TX packets: 1881; RX packets: 1880

Jan 31 17:08:51.790 GMT: Leg 2: CallID=3638; TX packets: 1879; RX packets: 1879

Also the voice gateway DSP output appears to show that there are active voice channels allocated however there are no voice calls showing on the gateway at the time. Is this a firmware problem with the DSP that could be causing this?

ACH-B8-RC1#show voice dsp

----------------------------FLEX VOICE CARD 0 ------------------------------
                           *DSP VOICE CHANNELS*
DSP   DSP             DSPWARE CURR  BOOT                         PAK   TX/RX
===== === == ======== ======= ===== ======= === == ========= == ==== ============
C5510 001 01 g711ulaw  4.4.24 busy  idle      0  0 0/0/2     08    0         0/14
C5510 001 02 g711ulaw  4.4.24 busy  idle      0  0 0/0/1     04    0         0/14
C5510 001 03 g711ulaw  4.4.24 busy  idle      0  0 0/0/0     00    0         0/14



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Manish Gogna Fri, 01/31/2014 - 09:45
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If the call is disconnecting as soon as it is answered then it points to a codec issue. Can you check the region settings between the gateway and called party and the codec on the gateway leg. If there is are diff codecs in picture is there a transcoder that is being used?



BSOC support Mon, 02/03/2014 - 03:22
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This is an intermittent problem so it is not affecting all calls. Also this has only just started happening. If this was a codec problem would it not affect all calls and be happening all the time?

The PSTN calls come into the gateway as per the above so I assume DSP resources on this gateway are being used to transcode/code analogue calls from the PSTN into digital calls on the customer network?

Can someone shed some light on the above message in the gateway logs or the DSP issue (also above)?

Many thanks


BSOC support Mon, 02/03/2014 - 03:34
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Also how would I troubleshoot a problem like this on the CUCM? SDI traces, CDR, RTMT or Wireshark?




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