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Silver

Transcoding Resources in 2800s

Is it possible to use the DSP resources (PVDM2-X on-board 2800 routers) to both terminate voice calls and provide DSP resources for transcoding. The 2800s currently handle two E1s but could potentially handle 4 E1s, and therefore two PVDM2-64s are required to terminate these calls.

On a related point, it has been suggested that if G.729 is required anywhere in the network (e.g. across a WAN), then G.729 could be enabled as the default codec because the loss in voice quality (as compared to G.711) is not that significant and then transcoding resources are not required. Are there are downsides to this; MoH quality, for example?

2 REPLIES
Hall of Fame Super Silver

Re: Transcoding Resources in 2800s

1) Definitely, as long as you have enough PVDMs you can share them between voice calls, and conferencing or transcoders

2) G.729 is recommanded for WAN calls, the voice quality is not as good as G.711, but acceptable. You don't need transcoders if you only have IP phones on your network, IP phones negotiate codecs and have build in transcoders. As to the Music on Hold it sounds terrible with G.729, G.729 is a voice codec and does a poor job to encode/decode music. I would recommand enabling multicast MoH and streaming it from remote router flash. This way you'll get G.711 MoH which does not have you traverse the WAN.

Chris

Green

Re: Transcoding Resources in 2800s

Hi, just as a quick note to complete what Chris wrote,for point 1.

Transcoding and normal voice termination can share the same DSP. Conference needs to use its own dsp firmware, hence it can not share the same dsp with transcoding or normal voice termination.

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