Hi Michael,
Thanks. I agree that it’s going to be a difficult job. The values involved are not easy to quantify.
Here’s the sort of thing I had in mind to start with: We are thinking of expanding on the Erlang B traffic calculator on our main site. This works out how many lines are required for a given busy hour traffic.
This can be translated to required bandwidth (taking IP/UDP/RTP headers into account), to give a bandwidth value. Header compression can then also be taken into account, although this seems a little more vendor specific.
I don’t agree that blocking isn’t an issue. I don’t think it’s good enough just to send as many calls as possible through an IP network until quality is compromised.
The approach that some vendors are taking is to apply Admission Control to the edge of a network. Rather than limiting the bandwidth allocated to voice, it limits the number of discreet voice calls which can be accepted before an alternative route is selected (eg. PSTN).
Considering the number of discreet voice paths which a network can accept is certainly easier for voice specialists (like to) to get our head round.
I agree that data comes into the picture as well, but I haven’t really worked out a way of factoring that in. I’d like to though. Do data planning engineers use any models similar to the Erlang models which us voice boys use?