This description is taken from ECMA-269, Section
12.2.29, "SubjectDeviceID".
12.3.29 SubjectDeviceID
The SubjectDeviceID parameter type represents a device which is the focus
of the action associated with the event
being reported.
Format and Status
This device identifier type may be one of the following (see CSTA
Device Identifier Formats for more information):
-
a character string when using the Diallable Digits and the Switching Function
Representation formats.
-
an integer value when using the Device Number format.
-
a value of �Not Known�.