main (intra-MSG and inter-MSG). Traffic mix - how big part of the traffic is IN traffic (needs more complex signalling). Type of processor - different processors have different call handling capacity. Impact of Traffic Distribution As mentioned before, the processor has to handle all the originating calls plus all the incoming calls. See Figure A4.20. With the assumptions that the traffic portion going to other networks is p0, the portion traffic going to other domains is p2 x(1 - p0) - and the traffic staying in the own domain is p1 x(1 - p0), then the number of calls per second can be calculated with the formulas in Figure A4.20. For simplicity reasons, the intra-MSG traffic has not been considered in the example. Numerical Example Figure A4.21 shows by means of a numerical example how the calculation can be done. In this example the total traffic in one domain is 200 000 X 0.1 = 20 000 Erlang. 10 000 Erlang is originating and 10 000 Erlang is terminating traffic. Transit Other networks Traffic volume Out from MSN network Traffic distribution ML/MGW ML/MGW Traffic mix Other domains Other networks 40% (po) Own domain MSN network 60% (1-po) Own domain 30% (p1) Other domains 70% (p2) No. of subscribers/no. of E1 traffic per subs. Figure A4.19 Call-handling capacity in a telephony server Appendix 4: Dimensioning Media Gateways and Associated Telephony Servers Other domains N (1-po) X p2/s Other networks Other networks N X ao X po/s N X ao X po/s Other domains N X ao X (1-po) X p2/s N = no. of subs Own domain E1 = no. of E1 N X ao (1-po) X p1/s ao = orig/sub S = mht N x ao/s N x ao/s Subscribers or E1s CP-calls per sec = N X ao X (1+po+(1-po) X p2)/s Figure A4.20 Call-handling in a telephony server Other networks 475 cps transit Out from MSN network ML 10G: 300 cps ML 20G: 570 cps 4000 erl ML/MGW ML/MGW 4000 erl 4200 erl Other domains (42%) 4200 erl Own domain (18%) 1800 erl 10 000 erl Other networks MSN network 200 000 subs (807 E1) Own domain 0.10 erl/sub(tot.) Other domains 120 mht CP - calls = 10 000/120 + 4000/