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Beginner

Audio quality, dropped calls from PRI line clocking..?

Hello

I am getting reports of a number of dropped calls and spotty audio quality from my users in a location where we recently upgraded the office to VOIP. Initially, I was on the phone to the carrier but they said there was no issue. Now I am thinking it may be related to the clocking of the PRI lines

I need some guidance on the best way to ensure the clocking is correctly sync'ed up so that there is no PVDM issues which may be resulting in choppy audio and/or dropped calls.

The inventory is a 3945e with an NM-HDV2-2T1/E1installed on slot 1 with pvdm2x64 on this.

On port 1/0 is a TDM e1 trunk with clocking set from 'line'

On port 1/1 is a TDM e1 trunk with clocking set from 'line'

On port 2/0 is a digital PRI line. This did not support clocking from the line so initially I was getting slips and errors. So I set the command 'clock source internal' and this got rid of the slips and errors.

The other commands I have are:

network-clock-participate slot 1

no network-clock-participate slot 2

network-clock-select 1 E1 1/0

network-clock-select 2 E1 1/1

So - could anyone please help and advise if one, It is possible for the audio issues to be a result of clocking incorrectly and two if there is a way to verify if something is wrong.

Show network-clocks

Network Clock Configuration

  ---------------------------

  Priority      Clock Source    Clock State     Clock Type

     1          E1 1/0          GOOD            E1

     2          E1 1/1          GOOD            E1

    10          Backplane       GOOD            PLL

  Current Primary Clock Source

  ---------------------------

  Priority      Clock Source    Clock State     Clock Type

     1          E1 1/0          GOOD            E1

4 REPLIES 4
Rising star

Audio quality, dropped calls from PRI line clocking..?

Hi,

Why are you so sure is related with the PRI clocking? If you migrade recently to VOIP it could be a QoS issue.

Regards

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Beginner

Audio quality, dropped calls from PRI line clocking..?

nope I'm certain it ain't qos

is there any guide available regarding clocking of pri lines etc

Hall of Fame Master

Audio quality, dropped calls from PRI line clocking..?

E1 PRI from telco, should have clock from line, and highest network-clock priority.

Then you would have to check again on "show controllers e1" and drop cause.

Highlighted
Participant

Re: Audio quality, dropped calls from PRI line clocking..?

http://www.cisco.com/en/US/products/hw/routers/ps1904/products_configuration_guide_chapter09186a008007dc3f.html

the relevane part is " to ensure a synchronised system, you must configure a master clock within the network , and distribute and recover the clock throughout the network.

If you cannot configure a synchronised system, then you can configure multiple clock sources on your network as long as they are accurate enough that the clocking on both clocks sources will match.

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