Specifications

VMMI Programming Exercises
GCA39-082 Rev 2, Issue 9/01 Page 22 Printed in the USA
Comdial makes the following boards that are capable of using E & M tie lines:
Board Comments
FXEMDD-DF
FXEMDD-MF
The FXEMDD-DF/MF boards are analog boards that
provide two wires for a tip and ring voice circuit and two
wires (the E & M line) to provide control signaling
between the systems.
When a local FX or DXP puts a request for service from
the remote equipment on the M lead, the remote
equipment detects this request on its E lead. As an
option it can also respond by putting an alerting signal on
its M lead.
DXPT1 and FXT1 The digital T-1 boards provide several line options on a
per channel basis, the E & M tie lines only being one of
those options. When you connect two Comdial systems
together using E & M protocol through the T1 lines,
designate one as the master and the other one as the
slave. In this application, only the slave system requires
a synchronizing card.
DXP Multi-purpose board
If you plan to use tone dial configured E & M lines with any of the boards mentioned above, you
may need to install one or more DTMF receiver cards into the Comdial system being used with
the tie lines. Typically, you will need one DTMF receiver for every 6 lines.
Connection and Signaling Considerations
Connection Types
The FX and DXP support two different types of E & M lines. The E & M Direct type is for
direct connection between two telephone systems. It is also known as a metallic connection. The
E & M Carrier type is for tie lines that run through a central office (CO) interface.