Vijay, that calculations are always done based on the busy hour traffic. You haven’t mentioned that. I take that in the busy hour every subscriber makes one call on average (the number may be more or less). Having 120 seconds of call hold time and 50k subscribers, it will give you a total of 1667 erlangs. Considering a normal distribution of 20% m-M calls and 80% M-L + L-M calls, you get 80% of 1667, 1334 Erlangs for POI Traffic. 0.01% GoS (That is what one is supposed to take for PoI calculations and 1334 erlangs you get 1447 Circuits (using erlang B) or 49 E1s. One to bear in mind is that generally you will not have all teh E1s going to same PoI. In that case you should either take the rule of thumb i.e. 22 Er per E1 or calculate the E1s seperatly for each PoI.