Latency between IP phones and Callmanager

[markcarat]

Hello,

We have a Callmanager cluster 8.51 in NYC and trying to set up IP Communicator at our Hungary office.  They will be using NY DIDs, so their inbound and outbound calls will be routed over to the PRIs at NYC.  What is the max latency or cisco recommendation between CM and IP Communicator? Any input will be appreciated.

Thanks

Mark

[paolo bevilacqua · Accepted solution]

There is no maxium set. Some people uses phones over sat links with RTT > 1 sec and it works fine.

[markcarat]

Thanks for the input Paolo.  The latency between NYC and Hungary is about 190ms.  We will give it a try.

Mark

[Chris Deren · Accepted solution]

From CUCM SRND:

The influence of latency on design varies, based on the type of Unified Communications service considered for remote deployment. If a voice service is hosted across a WAN where the one-way latency is 200 ms, for example, users might experience issues such as delay-to-dialtone or increased media cut-through delays. For other services such as presence, there might be no problem with a 200 ms latency.

There is also a good table showing estimated load download times based on the latency.

Chris

[Isidro Fernandez]

You should target below 150 ms one way delay, as per ITU-T G.114. Over that, the delay starts being noticeable for the speakers.

cheers

Isidro