Avaya 555-245-600 manual Endpoints in a three-site system Atlanta Boston Cleveland

			Call usage rates
Table 30: Endpoints in a three-site system
Endpoints	Atlanta	Boston	Cleveland
IP stations	1107	450	270
	(1080 IP	(450 IP	(270 IP
	Telephones + 27	Telephones)	Telephones)
	Road Warriors)
Circuit-switched	648	198	36
stations	(540 DCP stations	(180 DCP stations	(36 analog stations)
	+ 108 analog	+ 18 analog
	stations)	stations)
PSTN trunks	120 (DS0) PSTN	48 (DS0) PSTN	24 (DS0) PSTN
	Trunks	Trunks	Trunks
	(5 T1 facilities)	(2 T1 facilities)	(1 T1 facility)

First consider the 32 Erlangs of intercom CUR between Site 1 stations (Table 28). Site 1 (Atlanta) has a total of 1755 stations, 1107 of which are IP stations, and 648 of which are circuit-switched stations. So, 63% of the stations in Site 1 are IP, and 37% are circuit switched. Therefore, 63% of Site 1 intercom calls are generated by IP stations, and 63% of those calls are terminated by IP stations. Since 63% of 63% is 39.7%, 39.7% of Site 1 intercom calls are IP station to IP station. Similarly, 37% of the Site 1 intercom calls that are generated by IP stations are terminated by circuit-switched stations. Since 37% of 63% is 23.3%, 23.3% of Site 1 intercom calls are IP station to circuit-switched station.

Also, 37% of Site 1 intercom calls are generated by circuit-switched stations, and 63% of those calls are terminated by IP stations. Since 63% of 37% is 23.3%, 23.3% of Site 1 intercom calls are circuit-switched station to IP station. Finally, 37% of the Site 1 intercom calls that are generated by circuit-switched stations are terminated by circuit-switched stations. Since 37% of 37% is 13.7%, 13.7% of Site 1 intercom calls are circuit-switched station to circuit-switched station.

So, since 39.7% of Site 1 intercom calls are IP station to IP station, IP station to IP station call usage is 39.7% of the 32 Erlangs of overall Site 1 intercom CUR, or 12.7 Erlangs. Similarly, both the Site 1 IP station to circuit-switched station CUR and the Site 1 circuit-switched station to IP station CUR are equal to 23.3% of 32 Erlangs, or 7.5 Erlangs. Finally, the Site 1 circuit-switched station to circuit-switched station CUR is 13.7% of 32 Erlangs, or 4.4 Erlangs.

A similar process is used to break down the 12 Erlangs of intercom CUR into its components. There are a total of 648 stations in Site 2 (Atlanta), 450 of which are IP stations, and 198 of which are circuit-switched stations. So, 69% of the stations in Site 2 are IP, and 31% are circuit-switched. We have already determined that 63% of intercom calls that are generated in Site 1 are generated by IP stations. Similarly, 69% of intercom calls that are terminated in Site 2 are terminated by IP stations. Since 69% of 63% is 43.5%, 43.5% of Site 1 to Site 2 intercom calls are IP station to IP station. Also, 31% of intercom calls that are terminated in Site 2 are terminated by circuit-switched stations. Since 31% of 63% is 19.5%, 19.5% of Site 1 to Site 2 intercom calls are IP station to circuit-switched station.

Issue 6 January 2008 193