How many lines do I need? This topic has 3 replies, 1 voice, and was last updated 18 years, 7 months ago by tufail. Viewing 4 posts - 1 through 4 (of 4 total) Author Posts 21st June 2006 at 21:59 #45270 RadeomanGuest Can someone tell me how many T1 circuits I will need to accommodate 37 offices if each office average 11 calls per hour, and each call lasts about 7 minutes? I am rolling our a VoIP solution, but not sure how many T1s I need to order. 22nd June 2006 at 06:00 #45271 PrateekGuest Total erlang traffic = 11*7*37/60 = 47.48 So at 2% blocking probablity for 47.48 erlang you need 58 circuits. 1 T1 line consists of 24 circuits, If one circuit is reserved for signalling remaining 23 can be used for voice. So, Number of T1 requird = 58/23 = 3 (approx) 23rd June 2006 at 13:48 #45272 RadeomanGuest Thanks Prateek, I understood the math but using the free calculators gave me a wrong number. 28th June 2006 at 06:23 #45273 tufailGuest hi Radeoman becoz calculator uses 11*7*37/3600 that traffic will be lesser than the required. thanx hope that will help Tufail Author Posts Viewing 4 posts - 1 through 4 (of 4 total) The forum ‘Telecom Design’ is closed to new topics and replies.