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The general formula that is used to determine the expanded intercom CUR entries in
Table 27: COI matrix for Example 4: Expanded COI matrices (intercom CUR values only)
page 158 is:
CUR generated by stations of type t in Site i
and terminated by stations of type t in Site j
where:
"Type t" refers to IP or circuit-switched
Now that the intercom CURs have been determined, CURs that involve trunks will be
addressed. First, because Communication Manager systems are rarely used to route PSTN
traffic, all of the COI matrix entries that correspond to PSTN-PSTN traffic are zero. Next,
Table 22: Inbound COI matrix for the Uniform Distribution model in Example 2: Uniform
Distribution model
on page 151 and
Model in Example 2: Uniform Distribution model
correspond to inbound and outbound PSTN traffic.
According to
Table 22: Inbound COI matrix for the Uniform Distribution model in Example 2:
Uniform Distribution model
and terminates at Site 1 stations is 49 Erlangs. We have already determined that 63% of the
stations in Site 1 are IP and 37% are circuit switched. Therefore, the Uniform Distribution model
implies that 63% of the 49 Erlangs (that is, 30.9 Erlangs) is inbound to Site 1 IP stations, and
37% of the 49 Erlangs (that is, 18.1 Erlangs) is inbound to Site 1 circuit-switched stations.
Similarly, the Uniform Distribution model and
Distribution Model in Example 2: Uniform Distribution model
63% of the 49 Erlangs of Site 1 outbound PSTN usage (that is, 30.9 Erlangs) is outbound from
Site 1 IP stations through Site 1 PTSN trunks, and 37% (that is, 18.1 Erlangs) is outbound from
Site 1 circuit-switched stations through Site 1 PTSN trunks. Note that by an assumption in
Example 2: Uniform Distribution
originates at Site 1 stations. This completes the work for Site 1. Sites 2 and 3 are handled in a
similar manner, and the resulting completed COI matrix for
is provided in
Table 28: Completed COI matrix for Example 4: Expanded COI matrices
page 160.
=
number of type t stations in Site i
t
--------------------------------------------------------------------------------- -
f
=
i
total number of stations in Site i
number of type t stations in Site j
t
--------------------------------------------------------------------------------- -
f
=
j
total number of stations in Site j
Table 23: Outbound COI matrix for Uniform Distribution
on page 152 help us determine the entries that
on page 151, the inbound PSTN usage that arrives on Site 1 trunks
Table 23: Outbound COI matrix for Uniform
model, Site 1 inbound and outbound traffic only terminates and
t
t
f
f
intercom CUR from Site i to Site j
i
j
on page 152 together imply that
Example 4: Expanded COI matrices
Issue 3.4.1 June 2005
Call usage rates
on
on
159
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