Multi-Site IAX2 Call breakup

I have six sites all connected in a mesh topology through IAX2 trunks over IPSec. Most sites have asymmetrical Internet bandwidth, i.e, cable, dsl, so not a lot of upload bandwidth.
My PBX’s are setup like out of the box. The IAX settings are ulaw,alaw,gsm,G722 (i think) except that i ticked off low bandwidth on all. In looking at the logs, it appears that calls between sites are using GSM. My users are complaining about the calls breaking up in mid-sentence on intra-sites calls. Would i be correct in purchasing a G729 license for each PBX? What has your experience been?


You would be correct in reserving enough bandwidth for the call. You need QoS policies.

g.729 is useful if you want to reserve less bandwidth. It’s not a panacea as any droupouts will cause more loss of speech (more information packed in less space).