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G722/G729 wich one to choose ? (licence fee appart)


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G.729A is compressing the voice to 8 kbit/s, which is useful if you have limited bandwidth at the cost of sounding a little bit like tin-can. G.722 is using the same bandwidth as G.711 (64 kbit/s), but does a more clever encoding than G.711 so that the higher frequencies can be heard by the other party.


Whatever codec you choose, you need to be aware that whenever the call gets into the PSTN, it will be 99.99 % of the time on G.711 (a-law or u-law). If you are coming from G.729A, you have additional transcoding costs. Surprisingly, this is also the case for G.722: even though it is a better codec than G.711, you will have a inferior performance than in a system that uses only G.711. This is because translating from one codec to another codec can not lift the quality up (invent a better sounding signal) unless you have artificial intelligence engaged.


Ten or twenty years ago bandwidth was still a problem; but IMHO most offices today have no problem sending a megabit to the Internet, so G.729 is kind of outdated. G.722 sounds nice at first glance, but it is difficult to keep it along the path from caller to callee. IMHO today you get the best end-to-end quality still using the good old G.711 codec.

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thanks for your answer,


but then what's the deal with G729 licence fees ? how to use this codec for internal calls only ?

if i put G729 at the top of the codec list, will it be used for internal calls or will either internal calls fallback to G711 ?


by the way, should i use G711A or G711U ?


sorry for those many questions,





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It will be tricky to make a distinction between internal end external calls (you could set G.722 as the first codec for extensions, but G.711 for trunks). Most customers don't worry about the quality of internal calls as they don't directly generate revenue (smoke signs are good enough). The focus is on having a great outside perception with customers, and there the simple answer is that G.711 is the best codec.

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