Network Interfaces

LS Loop Start
GS Ground Start
PL Private Line (lease line)
RB Reverse Battery
A1 Type A Tie Trunk type I signalling
A2 Type A Tie Trunk type II signalling
B1 Type B Tie Trunk type I signalling
B2 Type B Tie Trunk type II signalling
CT Type C Tie Trunk
RL Release Link Trunk
OPS Off Premises Station
OPSP Off Premises Station Proprietary
DI1 Digital Interface
DI2 Digital Interface with signaling bits
DI3 Digital Interface containing encode analogue
MC Metallic Channels
IST ISDN S/T Reference
ISTA ISDN S/T reference with encoded analogue
IUB ISDN U reference Basic Rate Access
IUP ISDN U reference Primary Rate Access
DSC Digital Subrate Channels