I won’t go into the math, however, but I will appeal to intuition. Mathematicians may cringe at my example but I believe it is correct.
The basic principle is that the more servers (circuits) you have the better *potential* utilization there will be.
You can think of Erlang B as modeling a set of bank tellers serving customers that will leave if no teller is free (no queueing).
Assume there are 10 tellers and people are assigned to a teller based on the first letter of their name. (e.g. A-D goes to teller 1). If that teller is not free the customer leaves the bank and has to try again later. They cannot use another teller even though that teller may be free.
If we change this and say people can go to any teller as long as they that teller is free it should be apparent that the tellers will be better utilized this way.
The same principle applies to telephony. The more circuits in a group the better *potential* utilization there will be. By having a larger circuit group you are making a larger pool of circuits available to each call attempt.
Objective Systems Integrators Performance Management Solutions