ISDN Modem Initialization AT Commands

This article lists some modem initialization strings for the following Integrated Services Digital Network (ISDN) modems:

• Motorola Bitsurfr/Pro
• USR Courier I
• 3Com Impact
• 3Com Impact IQ

These AT commands may be useful for troubleshooting ISDN modem-related issues.

These following commands are ISDN modem initialization strings. You can use these commands if you are having connectivity issues or if your modem does not initialize or respond.

Motorola Bitsurfr/Pro

128K : AT&F&C1&D2\Q3%A2=95@B0=2%A4=1
64K : AT&F&C1&D2\q3%A2=2@B0=1%A4=1
V.120 : AT&F&C1&D2\Q3%A2=2%A4=1

USR Courier I

128K : AT*M=0*T1=00*V1=0*T2=00*V2=5&D2
64K : AT*M=0*T1=00*V1=1*T2=00*V2=5&D2
V.120 : AT*M=0*T1=00*V1=0*T2=00*V2=1&D2

3Com Impact

128K : ATS71=1S80=1&D2
64K : ATS71=1S80=0&D2
v.120 : ATS71=1S80=2&D2

3Com Impact IQ

128K : ATS71=1S80=1&D2
64K : ATS71=1S80=0&D2
v.120 : ATS71=1S80=0&D2

Using the Initialization Strings

Using the Modems tool in Control Panel:

1. Click Start, point to Settings, click Control Panel, and then double-click Modems.
2. Click your ISDN modem, and then click Properties.
3. Click the Connection tab, and then click Advanced.
4. In the Extra Settings box, type the appropriate initialization string, click OK, click OK, and then click Close.

Using HyperTerminal:

1. Click Start, point to Programs, point to Accessories, point to Communications, and then click HyperTerminal.
   
   NOTE: If HyperTerminal is not installed, please see the following article in the Microsoft Knowledge Base for more information about installing additional components:
   
   ARTICLE - ID: 188125  (http://support.microsoft.com/kb/188125/EN-US/ )
   TITLE : Windows 98 Components for Typical, Portable and Compact Setup
2. Double-click Hypertrm, type "test" (without quotation marks) in the Name box, and then click OK.
3. In the Connect Using box, click Direct To Com<x>, where <x> is the serial port number your modem is connected to, and then click OK.
4. In the Bits Per Second box, click 9600, and then click OK.
5. Type the appropriate initialization string and then press ENTER.
   
   NOTE: If you receive a "Can't open port" or "Port already open" error message, you may have a hardware problem, a resource conflict, or another program (such as a fax program) may be controlling the COM port.