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New Member

Voice quality gets poor on remote pstn calls

Hi, we do have a two cisco call managers 4.0, one in France and one in Angola .

The french cluster is connected to a voice gateway.

Someone configured international calls from Angola to go through the WAN (h225 Trunks with the gatekeeper controling ) from Africa to Europe and then the number dialled is translated in the CCM french cluster and putted to the voice gateway to go out.

Internal calls using short dials, between clusters working fine, but international calls show a lot of buffer underruns after a certain period. I wonder if this is the best way of doing it .

1) Shouldn't we just put the international calls from ANgola directly to the voice gateway (H323 registered) instead of goint to the CCM in france and then translate the number?

2) What happens in terms of rtp anf signalling protocols by setting up the system this way ?

3) What could be causing the problem?

Can anyone help?

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Re: Voice quality gets poor on remote pstn calls

1.Is it cheaper to place the calls from France? Does it save enough money to pay for the extra WAN bandwidth required? If yes to both, then it is a smart setup.

2.If the calls go through normally then you are OK. H323 handles high delay OK, though you may need fast start. I have had no issues with trunks over satellite links.

3. What exactly is the voice quality issue; choppiness, static, echo or? Do you have enough bandwidth? Is the gatekeeper limiting the number of calls to what the QOS can support? Do you have QOS configured? Does your WAN link provider have a SLA for jitter, delay, and packet loss? Do you have VAD configured? If you call cluster to cluster are you seeing any packet loss on the IP phones (hit ? twice)? Do you have the echo canceller enabled on the French gateway?

New Member

Re: Voice quality gets poor on remote pstn calls

The problems occurs with the INternational put/received from/to the voice gateway in France and related to Call Manager in Angola. The problem is delays in the conversation after some minutes.

Bandwidth is 160 k priority for voice over the SAT and then 600 k on MPLS to France

QOS in enable both on the SAT and MPLS

SLA for jitter, delay or packet loss. I need to ask (Sorry but i don't know the concept of SLA applied to this)

VAD - i need to check the french gateway (thats where it needs to configured ?)

Echo enabler - i need to check again

Let me check packet loss for cluster / cluster calls

Can you help, please ?


Re: Voice quality gets poor on remote pstn calls

What is your end to end latency? Can you do a ping from the French gateway router to Angola?

Cisco recommends that end to end delay be under 150 ms for best quality. Satellite links (minimum 250 ms one way) always experience high delay that is perceptible to users, but I'm sure that is a fact of life in Angola. Or is there terrestrial service (microwave or fiber) out for locally placed calls? If so your users would be happier if their calls hit the PSTN in Angola.

New Member

Re: Voice quality gets poor on remote pstn calls

Call Beginning Mobile Phone

rxtype g.729+txtype g729

rxsize 10 ms

txsize 20ms

rxcnt 002219

txcnt 004166


maxjtr 130

rxdisc 0000

rxlost 0041

rxsize is changing from 10 to 20 ms

o avgjtr is changing all the time 30, 39 43 54 74 51

maxjtr 289

rxlost 0144

rxlost 0191

tccnt 031813



rxlost 0201

Call ending

total connection 13 minutes

Ping from French voice Gateway router to Angola Call Manager

Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:


Success rate is 100 percent (5/5), round-trip min/avg/max = 702/730/765 ms

Maybe you are right and the PSNT in Angola would be a better user solution for internatinal calls

Can i have, please, your comments on the call

report ?


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