i have the exact question in my mind also. to my understanding, the trunk (american terminology) is used to connect the switches in the exchanges and is typically an E1 (lowest) in the telco world. However, my question is, in the Erlang B formula, it does not define what the trunk dimension is. Is it an E1, an E3 ??
The Erlang B formula basically says given the desired grade of service and the amount of traffic, we can work out the number of trunks required but what is this trunk size physically ?
Do you have any thoughts on this or have anyone enlightened you on it ?