Data compression


I want to know if there is a ways to compress data between two asterisk servers. The objectif is to preserve as possible the bandwidth.
In the documentation it is said that IAX uses less bandwidth than SIP but is there others ways to keep minimal use of the bandwidth.

Thanks for help

you need to go and read about the different codecs, g729, ulaw, alaw, speex, etc etc

Yes I have already read the section of the codecs and I made some tests
with the tool provided by astersikguru. But is there others ways to reduce more the compression?