User Guide ISDN Terminal Adapter MTA128ST-USB

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Chapter 4 - AT Commands, S-Registers, and Result Codes
* The MTA128ST-USB is manufactured in two builds. To determine the build of your terminal
adapter (TA), issue the ATI2 command in a terminal window. If the TA responds to the command
with MTA128ST-USB, then it supports V.110. If your TA resonds to the ATI2 command with
MTA128ST-USB-RC, V.110 support is not available. The MTA128ST-USB-RC will respond to the
&F1 command with an ERROR..
Command: &Jn
Function: Automatic Channel Bundling
Values: n = 0 or 1
Default: n/a
Description: &J1 causes the TA to dial the number given in the dial string again to set up
a bundled PPP connection (also known as MultiLink PPP). Only works with
the PPP/ML-PPP protocol ( !Z=9 ). &J0 will not dial the given number again
and it will not interfere with the given dial string meaning that if there are two
numbers in the dial string (like ATD5551000&5553000 ) the TA will dial both
of those numbers. &J0 does not disable the dialing of a second number if a
second number is given in the dial string.
n=0 disables automatic channel bundling
n=1 enables automatic channel bundling
Command: &Rn
Function: CTS Control
Values: n = 0, 1, or 2
Default: &R1 (CTS forced high)
Description: Allows you control the state of the CTS (Clear to Send) signal on the
RS232E/V.24 interface. Normally the CTS signal follows the state of the RTS
signal when the MTA128ST-USB is online.
&R0 CTS acts normally; i.e., it follows RTS
&R1 CTS is forced high, but still provides online flow control
&R2 CTS is forced high, but it drops on disconnect for the period of time
set by S10. CTS still provides flow control when the TA is online.
Command: &Sn
Function: DSR Control
Values: n = 0, 1, or 2
Default: &S0 (DSR high)
Description: Controls state of DSR (Data Set Ready) signal on RS232E/V.24 nterface. A
high DSR signal indicates to the computer that TA is ready to transmit data.
&S0 DSR is always high.
&S1 DSR acts normally; that is, it follows the state of the CD signal,
which goes high when the MTA128ST-USB detects a carrier signal,
and goes low when the carrier signal is lost.
&S2 DSR is always high, except on disconnect, when it drops for the
period of time set by S10 and then goes high again.