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VoIP call quality issues with 1750-2V and FXS/FXO interfaces

hi.

We have some troubles using 1750-2V (IOS 12.2(1))with FXS/FXO interfaces, in a 64k leased line.

We are using IP precedence, RTP header compression, MLPPP & Interleaving and a G.729a codec.

If i use the voice channels without traffic everything is Ok, but when i stress the line with data, some interruptions (mute) happens with the voice communication, and in some cases the voice communication is disconnected.

Sometimes when the line is very stresses with data and i try to initiate a voice call, sometimes the call is success but sometimes the peer phone ring and when i hang up the voice communication can't be established. (i need to hang up and try again),etc.

We tried with a lot of qos configuration but this things continue, do you know any solution for this kind of problem ?

Thanks

2 REPLIES
Cisco Employee

Re: VoIP call quality issues with 1750-2V and FXS/FXO interfaces

Are you using either LLQ or ip rtp priority with your MLPPP configuration? IP precedence is not enough on its own to provide the strict priority that voice traffic requires.

http://www.cisco.com/warp/public/788/voice-qos/voip-mlppp.html

http://www.cisco.com/warp/public/788/voip/voip_ppp_lowbw_rtp_prio.html

http://www.cisco.com/univercd/cc/td/doc/product/voice/ip_tele/solution/4_design.htm

New Member

Re: VoIP call quality issues with 1750-2V and FXS/FXO interfaces

Thanks for your answer, i'm using WFQ, IP precedence, tcp and rtp header compression, rtp priority and MLPPP.

I'll check the links and i'll try again.

Fernando.

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