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New Member

IP Phone to IP Phone calls

I have an issue mentioned below:

If a users on Phone A (ext. 1237) calls a user on Phone B (1238) the connection establishes, however the audio is delayed 6 -10 seconds, in both directions.

Only calls between IP phone to IP phone have the audio delay issue, if any of the local IP phones receives or connects a call via the voice gateway, there is no audio delay.

I would be grateful if someone could help me in this case

  • IP Telephony
18 REPLIES

Re: IP Phone to IP Phone calls

Try to ping from phones A's default gateway to phone B see if there is a delay in the network.

Also you could check to see if there is high CPU utilization that could be causing the problem.

HTH

Please rate helpfull posts

Jason

New Member

Re: IP Phone to IP Phone calls

Hello Jason,

Thanks for yours prompt reply. I would just like to mention again :

Only calls between IP phone to IP phone have the audio delay issue, if any of the local IP phones receives or connects a call via the voice gateway, there is no audio delay.

Re: IP Phone to IP Phone calls

OK so are all the phones on the same LAN?

Jason

New Member

Re: IP Phone to IP Phone calls

Yes Jason, all the phones are on the same LAN.

The CCM Cluster is located across the WAN, with all the appropriate QOS supporting the IP Phone signalling. There are no VoIP call connections cross the WAN, the voice is all local, calls to and from the PSTN are via the local 3825 router.

Additional details:

The Cisco Call Manager service is on version 4.1 (3)sr5b - hardware is MSC-7835 H1

IP phones loads are:

7960, P00308000500

7940, P00308000500

7912, CP7912080003SCCP070409A

Gold

Re: IP Phone to IP Phone calls

If all the phones are local to the remote WAN, can you check the IP Address being shown for the Phones on CallManager when you search for the specific phones. Note that incase the IP Address being displayed on CCM Admin page does not match with the IP Address on the Phone, this could be the problem. When CM sends a message to the both the Phones to start Media exchange, it gives the IP Address as per the IPs Addresses that is shown on the CCM Admin page as the CM believes that is the IP. So if the CM has the phone registered using a NATed address and the phone would try to send audio to the NATed IP of the Phone and not the Local LAN IP Address.

New Member

Re: IP Phone to IP Phone calls

hi did you mean we can perform the steps mentioned by you when These are all Cisco IP phones, registered on Cisco Call Manager cluster and The phones reside on the same local area network,

Gold

Re: IP Phone to IP Phone calls

From what I have understood, the Phones are local to one LAN and the CallManager is over WAN. Is that right ??

If the above is correct, can you check the IP Address being displayed when you do a search for this phone and confirm that the IP Address is the same as the phone assigned to the phone and not a NAT IP Address.

New Member

Re: IP Phone to IP Phone calls

yes you are right. the phones are local to one LAN and CAllManager is over WAN.

Alright I would check the steps mentioned by you and would let you know the results.

Let me know what if there is IP address mismatch. what needs to be done here?

Yours suggestions would be extreme helpful as you have got the scenario perfect.

Gold

Re: IP Phone to IP Phone calls

If that true, check this tac cc case. This should help you on how to handle it:

http://www.ciscotaccc.com/kaidara-advisor/voice/showcase?case=K12197028

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