Is there a single MIB we can use to show the number of simultaneous isdn calls on 3845 and 2811 router using snmp or maybe a perl scipt?
I have seen this link referenced a few times ....
and just found this one as well with a quick google search
It really all depends on what router you're using, what SNMP tool you are using, and what protocol on the gateway you are using, i.e. MGCP, H323, SIP, etc.
here's the google search:
but you could substitute mrtg with cacti, and add mgcp or h323, etc, until you find exactly what you are looking for.