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Cisco VOIP and satellite latency

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mando1

IS-IT--Management
Jun 27, 2001
60
US
Been fighting with latency issues using nortel voip trunking and BCMS. I spoke to a high level Cisco gov major accounts rep who says they have been using voip phones over satellite in Iraq with good luck. Any body out there use call maanger over high latency satellite links ?
 
What's your latency and what issues are you experiencing that you want assistance with?
 
Hello,

i am interested also, we have implemented Cisco IP telephony over satellite, but with small problems we dont know how to fix. We dont know if the problem its in our side or in the satellite part, managed by Schlumberger, the bandwith its 2MBs.

The problem is that after a variable number of minutes calling to a phone outside of the network(mobile or analog), there are problems of jitter in the IP phones, the external phones does not have problems. The calls in the network works good, and we are using an antenna and its IDU on each location.

I am looking how to fix it without luck for the moment.

 
Latency isn't normally resolved by switching PBX vendors. Are you implementing any QOS currently? What are using for your network infrastructor?
 
We have a latency about 550ms.

About QoS, we only do classification and marking, giving the higher priority to the voice. The IDU from Schlumberger must look our marks and send the traffic with that priority.

for the infrastructor we are using 2821 routers to connect to the WAN and 6500 switches for the LAN.

 
150ms is the maximum latency before you experience voice degradation.

Your connection at 550ms is way beyond that and qos will be able to make it a bit more bearable but will never fix it.

No magic fix here besides getting a reliable link with less than 150ms latency sustained at all times.
 
with Satellite links, i think 500ms is normal.. am i wrong???
 
I am not saying it is not normal. I am saying with 550ms latency voice quality will suffer greatly.
 
Its ok whykap, i know 150 is the limit for voice, but the only solution for our network is using the satellite WAN.

 
150 is Cisco's limit and not real life.
i have had 250-275 ms and voice quality was fine.
 
So you would deploy IPTEL in an environment that has a 275ms latency with no second thoughts?
 
It was running over a VPN using a Verizon card in a laptop.
The 250-275 ms I was getting was not affecting quality at all.
And no we would not deply IPT in a production enviroment...but it does work
 
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