Which CODEC should I use?

My DrayTek Vigor 2800 connected to DreyTel offers me a choice of the following CODECs, which one is considered best?

G.711MU
G.711A
G.729A/B (the default one)
G.723
G.726_32

I guess some use more bandwidth than others, but does that only result when the VoIP circuit is actually being used?

Thanks

G711A is the European default - best quality - uses most bandwidth, but only when in use as you say.

G711 is the standard. The others probably won't work...

the best quality would usually be the 711 ones, and 711a is the UK/European norm for telephony. This does however use the most bandwidth, about 100 kbits/s both ways when a call is connected.

729 is an efficienct codec that uses a lot less bandwidth with acceptable quality. It does have a processing load and there can be licensing issues so not all devices or services support it. It would be a good preferred codec for efficiency unless you have issues with quality or the service don't support it.

726_32 I hadn't seen before - "The most commonly used mode is 32 kbit/s, since this is half the rate of G.711, thus increasing the usable network capacity by 100%. It is primarily used on international trunks in the phone network. It also is the standard codec used in DECT wireless phone systems and is used on some Canon cameras."

Wikipedia entries for the codecs are quite good explanations.

In the end you need something supported by your provider or by the called party.

I have 2 on my PAPT2 which one should i use? G711U/G711A ??

711a for Europe, 711u for USA. Not sure it matters but it may save something connecting to the PSTN from having to transcode it.