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New Member

AUDIO DELAY WHEN ANSWERING

Hello,

I am facing problems with audio delay when answering phone calls. Sometimes, when we receive a phone call, even after picking up the phone the other person still hears ringback.

After around 7 sec, the call gets connected. Once the call is connected,

there is no audio delay. It happens only when the bandwidth usage on the WAN

link is high.

Is it a "QOS" issue and if so then how to rectify the issue?

Could someone help me on this.

4 REPLIES
New Member

Re: AUDIO DELAY WHEN ANSWERING

Ensure that you have the voice traffic in CoS1 (EF) and signalling in CoS2 (AF). I have encountered this problem before; we changed the CoS and increased the AF bandwidth.

New Member

Re: AUDIO DELAY WHEN ANSWERING

Hello,

Could you please throw more lights on this as to how to approach towards the resolution, where exactly to change the settings

New Member

Re: AUDIO DELAY WHEN ANSWERING

You ideally need to VLAN your voice and data network, and give each network a different subnet. For example Data 10.1.0.0 and Voice 10.10.0.0.

Then if you are using ACL's on your routers

for the Voice traffic:

access-list voice permit udp 10.10.0.0 0.0.3.255 any range 16384 32767

access-list voice permit udp 10.10.0.0 0.0.3.255 range 16384 32767 any

For the Voice Signalling traffic;

access-list voicesignalling permit udp 10.10.0.0 0.0.3.255 eq 2427 any

access-list voicesignalling permit udp 10.10.0.0 0.0.3.255 any eq 2427

access-list voicesignalling permit tcp 10.10.0.0 0.0.3.255 eq 2428 any

access-list voicesignalling permit tcp 10.10.0.0 0.0.3.255 any eq 2428

access-list voicesignalling permit tcp 10.10.0.0 0.0.3.255 range 2000 2002 any

access-list voicesignalling permit udp any range 1718 1719 any

access-list voicesignalling permit udp any any range 1718 1719

access-list voicesignalling permit tcp any eq 1720 any

access-list voicesignalling permit tcp any any eq 1720

access-list voicesignalling permit tcp 10.10.0.0 0.0.3.255 range 11000 11999 any

access-list voicesignalling permit tcp 10.10.0.0 0.0.3.255 any range 11000 11999

Set these ACL's to use the different priorities on the Router.

If of course you are using DSCP, it will be much, much simpler. You may even choose to trust the endpoint (phone) all the way through the LAN and WAN.

Hope this helps

Paul

New Member

Re: AUDIO DELAY WHEN ANSWERING

Paul,

I am a bit confused as I am new to this.

I have few queries:

1) How to ensure voice is in CoS1 (EF) and signalling in CoS2(AF).

2) I am attaching herewith the configuartions. Could you please go through it and let me know what changed I need to go through.

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