Tieline Commander G3 TLR300, Reference Manual

Page: 261 / 383

Section 29: X.21 Tab
T ieline
Page 261
T E C H N O L O G Y
29.6. X.21 Call Control Type
This menu configures whether you are connecting using
X.21 in either C Signalling or Permanent Link modes.
29.6.1. C Signalling Mode
In
C Signalling
mode, a ‘C’ (Control Signal) is used to control the connection.
An ‘I Signal’ (incoming call signal) is used to indicate the presence of an
incoming call.
When dialing from one codec to another, the dialing codec (DTE1) changes
the C Signal from off to on to initiate an outbound call. At the codec (DTE2)
receiving the call an ‘I Signal’ (‘Indication’ or incoming call signal) changes
from off to on, indicating the presence of an incoming call. The codec
receiving the call then initiates a C Signal state change, from off to on, which
causes the I signal at the calling end to change its state from off to on. This
completes the call connection process over X.21.
To clear a call, press HANG UP on either codec to change the C Signal from
on to off. This will terminate the connection between the codecs.
29.6.2. Permanent Link Mode
In essence, X.21 connections in
Permanent Link
mode behave similarly to
making a call in POTS leased-line mode.
Very Important Note:
Session data is automatically turned off in
Permanent Link
mode. In this
mode ensure that both codecs are pre-programmed to operate using X.21
and with the same algorithm and bit rate settings etc.
When dialing from one codec to another, the dialing codec (DTE1) changes
the C Signal from off to on to initiate an outbound call. A call is initiated
when a user presses the
ENTER/DIAL
button on the dialing codec. Unlike in
C Signalling
mode, the I (CTS) signal is ignored.
An operator must manually press the ANSWER button on the answering
codec (DTE2) to accept the call. Please note that there is no auto-answering
in this mode.
To clear a call, press HANG UP on both codecs. This will terminate the
connection between the codecs.
If you require more information on session data and how it works, please see
the section titled Data Transfer & Using 3
rd
Party Devices.