Voice quality problem on CUCM 9.1

[aminedahel]

Hi, everybody,

I am working on a voice network using the CUCM 9.1, knowing that there are multiple sites controlled by a cluster of 5 CUCM.

Users experiment calls with bad quality,

the WAN provider is saying that the IP network is ok.

the LAN provider is saying the LAN network is ok

But the the SIP provider is saying that he noticed that therer is a packet loss and he said that the problem resides most liekly at the CUCM network.

What could possibly be a problem in the CUCM that causes these bad quality problems in phone calls.

Best regards.

[Manish Gogna]

This description is quite vague right now. Is the issue only seen with phone calls over the WAN link or with the calls on same LAN as well? If it is only with calls over the WAN then you need to concentrate on a few things:

Gather the phone models affected and their firmware versions.

Detailed network topology info based on which packet captures will be required to check at what point the voice related issues creep in.

HTH

Manish

[aminedahel]

Thank you all for your feedbacks, I really appreciate.

@Manish Gogna: phone model affected so far is 6941, an upgrade will be planned to do this upgrade.

@Cedrick_Cisco: there are two load balancers,  but they are used to load balance service requests only (registration, Extension Mobility,...), why should i restart the TFTP server?

@m.batts: When it comes to calls to the PSTN, all calls are forwarded through an SBC.

@Billy JOWEL: it's aminedahel :) , these bad quality  problems are only encountered to the external calls.

[Cedric_Cisco]

Hi aminedahel,

thanks for details.

if you have 2 Load balancers, you have to verify if you use bgp between them and if any provisionning tool is used.

Regarding TFTP Cucm request, I had the same problem and the root cause was axl requests from phones to tftp server, so restarting it will refresh data replication and it has impact on voice quality

Best Regards.

Cedric

[Cedric_Cisco]

Hi aminedahel,

I had the same issue few months ago, this kind of problems is often related to load balancer.

please check the following steps:

- utils dbreplication runtimestate on CUCM (Pub)

- If you have the status connected for all nodes with value = 2 , thanks to restart your load balancer (F5 or another product). If it doesn't resolve the issue, you'll have to restart CUCM (But only TFTP server).

Hope it'll help you. 

Best Regards.

Cedric

[je.gaudin]

.

[m.batts]

This is most likely a QOS issue on the WAN , you need to ask you're WAN provider what level of QOS you have.

"the WAN provider is saying that the IP network is ok" = this probably just means there were no faults on the circuit.

You don't say where you're Telco connectivity is , does each remote site have its own breakout?

[Mael BOURGET]

Hi aminedayo,

we must have a better description of you network architecture, to help you.

Bad quality calls are always PSTN calls ? Or inter site, intra site?

Thank's,

Bill

[Mael BOURGET]

@Billy JOWEL: it's aminedahel :) , these bad quality  problems are only encountered to the external calls.

Incoming calls or outgoing calls?

Is a local PSTN gateway, on a T1 access ? 

What can you see in the CDR/CMR record about packet loss, jitter and co ?