# "Consider a simple telephone network consisting of two end offices and one intermediate switch with a 1Mhz full duplex trunk between each end office and the intermediate switch. Assume a 4-Khz channel for each voice call. The average telephone is used to make four calls per 8-hour workday, with a mean call duration of six minutes. Ten percent of the calls are long distance. What is the maximum number of telephones an end office can support?"?

Hello to everybody, please provide the solution.

14-11-2012

28-12-2012
"Each telephone makes 0.5 calls/hour at 6 minutes each. Thus a telephone occupies a circuit for 3 minutes per hour. Twenty telephones can share a circuit (although this 100% utilization implies long queuing delays). Since 10% of the calls are long distance, it takes 200 telephones to occupy a long distance (4 kHz) channel full time. The interoffice trunk has 10^6/(4 × 10^3) = 250 channels. With 200 telephones per channel, an end office can support 200 × 250 = 50,000 telephones. Source: http://in.docsity.com/en-docs/Cellular_Systems__Packet_Switching_Networks-Wireless_Networking__LAN_and_Computer_Networks-Quiz_Solution_"
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28-01-2013
There must be some formula from the class you took to get this question...I don't know it, but I'd guess that assume 6khz bandwidth for each active phone line, each phone used 24 minutes a day. Use the 6khz to find number of channels per line available, and 24 minutes use per 8 hours (480 minutes) gives 20 time the number of phones (1Mhz divided by 6Khz). Of course, there is some random factor, how many phones are actually in use.
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