Compression question

[PureChimpie]

I have a scenario whereby I am rolling out a hosted Mitel solution on ISS servers and Gamma SIP trunks. I am looking for some clarification re call compression.

HP DL380 G7 servers runninng MCD5 SP2 PR1

I have 4 x ISS servers, 2 x user gateways (UG's) and 2 x trunking gateways (TG). Off one of the UG's will have a number of branch offices (approx 20 devices) with DSL lines providing the WAN connectivity with QoS. These users I would like to use G729 compression to preserve the bandwidth. The other UG and TG are head office and G711 is fine there.

I have put the UG in a different zone (network element form) to it's TG and also added the users into their own compression zone, IP trunks are set to auto compression. I am happy that I am getting G729 when dialling across the IP trunks to the other UG and to other zones within my UG, I can see this in the voice quality stats.

My question is will this be same when dialling externally over the SIP trunks? I am hoping with the existing configuration I will get the following outcome:

Branch IP Phone - - - - - > UG - - - - - > TG - - - - - - > Gamma SIP
G729 G729 G711


This is not live yet and any thoughts would be greatly appreciated!

Thanks

 

[DoubleUT]

If your SIP trunks are also setup in an other zone the system will try to get G729 as codec used. It will be send as the preferred Codec. If the Provider answers with not supported or something like that the next choise will be G711. There is no way to force these connections to G729.

 

[LoopyLou]

Agreed you can only get compression if the carrier supports it.

I'd tell you a UDP joke but I'm afraid you won't get it. TCP jokes are the best because you always get them.

 

[PureChimpie]

Ok, so even though the SIP trunks are on a different ISS and in a different zone to the IP sets, if Gamma (SIP provider) do not support the G729 codec it falls back to G711? This was my fear and I know the order was placed on G711 and not G729! It can be changed, but at a cost!

Also, would the trunk gateway (connecting to SIP SBC) require additional compression licenses to support this? I know the ISS has built in compression, but just trying to cover all angels as this solution goes in soon!

Thanks