Cisco Call Manager connected to Asterisk Server (Intel(R) Xeon(R) CPU E5-2630 0 @ 2.30GHz)x12, RAM 32GB. Conference app is confbridge. Voice quality is dropping after ~160 people with g729 and ~70 with ulaw. At the same time if we call from asterisk sip account (using zoiper) than voice quality is good for other participants.
What can be the issue ? Thanks
On
That is high number of channel
At that level on your host sound is became not perfect.
Zoiper have jitter buffer enabled, CCM- have no JB by default. So on zoiper you have more delay and less chance spot voice issues.
You can decrease load by mutting most of people in conference or spliting conference into two or three. However that require expert level in asterisk's dialplan.
Other posible issue - bandwidth. G711u(ulaw) use more bandwidth if compare with g729
Issue was inside CUCM (Cisco Call Manager) it had limit in bandwidth of 20Mb/sec so we couldn't handle more people in single room.