[Users] voip charging by ISP's

[Iqbal]

Hi

i was looking into a model where ISP may charge (SBC is already thiking 
of charging Vonage :-)), now if an ISP wanted to charge, all they would 
need is to extract the INVITE, BYE and all the stuff in the middle, to 
do some billing per VoIP provider sending traffic on there network, is 
anyone aware of any sniffers which could do this not from a proxy, but 
from the network level at a ISP end.

Iqbal