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New Member

What is the difference?

I'm a bit confused between the difference between the following 3 ways of setting up PSTN fallback if WAN bandwidth is insufficient in GK scenario

Say I want to call extn 3xxx on the remote office. The intercluster prefixs are *801, and the PSTN digits for the site is 9231-3xxx.

Method 1:

Configure a route list that contains two route groups. The first route group contains the intercluster trunk that routes outgoing calls over the IP WAN. Second route group contains the Voice Gateway.

Method 2:

Do everything on the Voice Gateway:

dial-peer voice 1 voip

destination-pattern 8013xxx

session target ras

preference 0

dial-peer voice 2 pots

destination-pattern 092313xxx

port 1/0:23

preference 1

Method 3:


Another extra Q regarding bandwidth for GK.

According to Cisco SRND, GK uses double the bandwidth as the codec call rate, so...

G.711 - GK uses 128kbps

G.729 - GK uses 16kbps

However, this is excluding all Layer 2, IP & RTP overhead... so when i am planning for number of calls, what values should i use as 'bandwidth per call'?


Re: What is the difference?

The following calculations are used:

Total packet size = (L2 header: MP or FRF.12 or Ethernet) + (IP/UDP/RTP header) + (voice payload size)

PPS = (codec bit rate) / (voice payload size)

Bandwidth = total packet size * PPS

New Member

Re: What is the difference?

Hi carenas123,

Is there any reference or tables of some sort that will outline what a GK uses for calculating a G.711 & G.729 call?