Feature calculations 4-5
Calculations with Integrated Message Service (IMS)
This method is used when a system is equipped with IMS. The following is
assumed:
-
Only messaging calls from 2500 sets require
DigitoneReceiver
service
-
50-50 split of originating and terminating calls and 135 seconds
average call holding time were assumed in Step (a).
-
50% of calls from 2500 sets were intra-PBX calls Step
(b).
-
In general, a caller will not wait until the completion of Recorded
AMOMCement
to act (press message button or transfer to attendant).
The average time is listening to an announcement is four seconds, (Step
d).
-
If the actual number of 2500 sets is not known, assume it to be 60% of
total lines.
Procedure 4-3
Calculations with IMS
1
Calculate originating calls from 2500 sets of the PBX.
Calls from 2500 sets = CCS/line x 100 x Qty 2500 sets/(2x135) = A_-
2Calculate intra-PBX calls from 2500 sets.
Irma-PBX 2500~set calls = A x 0.5 = B
3Calculate calls requiring service of DTR.
Calls to DTR = B x 0.5 = C where 0.5 is the fraction of B which goes to
the messaging service.
4Calculate traffic (CCS) to DTR.
Messaging CCS to DTR = C x 4/100
Messaging CCS should be added to the total DTR traffic to determine
the overall DTR requirements.
System engineering 553-3001-l 51
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