In this example:
a. COS 1 can make calls to all extensions.
b. COS 2 can make calls to COS 1 only. (COS 2 cannot make calls to COS 2.)
c. COS 3 can make calls to COS 3 only.
COS 1
Extn. 100 Extn. 101
COS 2
Extn. 102 Extn. 103
COS 3
Extn. 104 Extn. 105 Extn. 106
Conditions
•Internal Call Block also prohibits certain features, such as Walking Extension and Walking COS, from being
performed between certain extensions.
•Any extension can make an Operator Call regardless of the Internal Call Block setting of its COS. (®
12.1.5 Operator Features)
•Because each doorphone port is assigned a COS, the Internal Call Block feature can restrict certain
extensions from calling certain doorphones. (® 4.1.11 Doorphone Call)
PC Programming Manual References
4.13 [2-7-3] Class of Service—Internal Call Block— COS Number of the Extension Which Receive the Call
from Other Extension 1–64
5.12 [3-5-1] Incoming Call Distribution Group—Group Settings—Main— COS
6.1 [4-1-1] Wired Extension—Extension Settings—Main— COS
6.10 [4-2-1] Portable Station—Extension Settings—Main— COS
7.1 [5-1] Doorphone— COS
7.6 [5-4] External Relay— COS Number
Feature Manual References
3.1.19 COS (Class of Service)
170 Feature Manual Document Version 2008-11
9.1.14 Internal Call Block