Vanguard Managed Solutions Vanguard 6435 - Handbuch (Seite 31)

About the Vanguard 6435/6455 1-13
PRI Supplementary Service
Figure 1-10. D-Channel Only Messages
Frame Relay
QSIG
QSIG
PBX
PBX
QSIG
101
201
401
PBX
1) Active Call between User @101 & User201
2) User @101 tries to make call to User @101
3) PB @101 sends back busy indication
4) PBX @410 "camps on" User @101 using
"D" Channel Only Messages
5) PBX @401 places call when User @101 is free