[Asterisk-Users] Asterisk <--> Cisco router

[Joseph]

What codec should be used to connect a * box to
a cisco router which has a t1 with 24 trunks coming in?

My router voip dial plan looks like this:

dial-peer voice 2 voip
 destination-pattern [1,2,,3,5,8]..
 session protocol sipv2
 session target ipv4:10.x.x.x
 dtmf-relay cisco-rtp
 codec g711ulaw
 no vad
!

The problem I have is when more than one call is on it,
sometimes the quality gets very bad.

If more than one access the conference room it starts to 
blip real badly. 

Thots, ideas greatly appreciated.
-- 
respectfully, Joseph
                       ------=============