
CHAPTER 6 NDA-24305
Page 28 6
Revision 1.0
Q-SIG (CIRCUIT SWITCHED BASIC CALL - ETSI VERSION)
1. Q reference point
The Q reference point is not expected to be a physi cal inte rface b ut is sh own in conce ptual terms in t he fi gure
below.
The Q-Sig protocol creates Layer 3 messages for inter-PT N (PBX) signaling.
Control Plane Protocol Model
Note: Conforming to Q921-a (PBX-PBX Interface)
PBX
Call
Control
Protocol
Control
Data Link
Layer
Physical
Layer
PBX
Protocol
Control
Data Link
Layer
Physical
Layer
DTI DTI
QQ
Protocol defined
Layer 2 Note
in this standard
Layer 3
PBX to PBXCall
Control