For voip i would think you mean H323. We do have CAC
support on voice gateways. The feature needed is
Call Admission Control for H.323 VoIP Gateways and its suported in
12.2(8)T 12.2(4)T 12.2(4)T3 12.2(4)T1 for most platform e.g
175X , 26XX, 36XX etc.
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122limit/122x/122xa/122xa_2/ft_pfavb.htm
For Avvid , i.e ca;; manager the CAC is done using "location" and maybe "region" for calls admission
over Low speed WAN bandwidth.
Say you have two site A and B with call manager located in site A, you might say site A is in region 1 in a Lan location using
bandwidth of 100,000KB/s. Also put site B phones in region 2 and limited to the WAN bandwidth so we put
site B devices in location WAN using say 128KB of bandwidth.
If we used default codec for all phones, then at g711 using 80KB of bandwidth, only one call would be allowed to be connected over the wan link
by the call manager, because it deduct the bandwidth uses presently from that available 128 - 80 =48KB/s. No other calls is admitted on that bandwidth.
However here's were region comes in. You set all phone in region 1 to use g711 over LAN and g729 for communication with device in region 2 and vise-varsa the remote devices.
Now if a call is connected between region 1 device and region 2 device, g729 is used hence the bandwidth deducted is 26KB and we can still admit more calls at 26KB till the bandwidth left after each deduction can support one voice conversation.
http://www.cisco.com/univercd/cc/td/doc/product/voice/c_callmg/3_1/sys_ad/3_1_2/ccmsys/a02cac.htm
