HP Survivable Branch Communication zl Module powered by Microsoft Lync Planning and Design Guide 2011-02

2-10
Design Considerations
Planning Call Capacity
Table 2-6. Supported Calls per Telephony Card
You examine Table 2-6 and determine that, whether using T1 or E1, you can
purchase a Two-Port T1/E1 Telephony Card, which supports 48 or 60 calls. For
the SBM’s second slot, you could purchase either a Four-Port FXS Telephony
Card, which allows for the future installation of more analog devices like fax
machines. Or you could purchase a Two-Port FXS/Two-Port FXO Telephony
Card, which provides two ports for the fax machines and gives you two more
channels for calls.
Example 2. You do not have accurate records for PSTN calls. Therefore, you
use Microsoft guidelines to estimate. You have about 200 users at light usage,
400 users at medium usage, and 200 users at heavy usage. Therefore, you plan
for 93 concurrent calls. You do not have any fax machines at this time.
Table 2-7. Estimate PSTN Call Requirements (Example)
Examining Table 2-6, you determine that, if using T1 lines, you could purchase
one Four-Port T1/E1 Telephony Card to provide for all your needs. You could
also purchase two Two-Port T1/E1 Telephony Cards; however, the former
option allows you to use the other slot for future needs.
Telephony Card Total Supported Calls
Per-Card
Total Supported
Analog Devices
(such as Fax)
Single-Port T1/E1 Telephony Card T1 = 24
E1 = 30
0
Two-Port T1/E1 Telephony Card T1 = 48
E1 = 60
0
Four-Port T1/E1 Telephony Card T1 = 96
E1 = 120
0
Four-Port FXS Telephony Card 0 4
Four-Port FXO Telephony Card 4 0
Two-Port FXS, Two-Port FXO Telephony Card 2 2
Usage Level Number of Users at
That Level
Estimated Calls Total Estimated Calls
Light X = 200 X/15 = A = 13 A + B + C = D = 93
Medium
Y = 400 Y/10 = B = 40
Heavy
Z = 200 Z/5 = C = 40