How can I check if my modem is Class 1, 2 or 2.0 compatible?

15 October 2003

Whether a modem is Class 1, 1.0, 2 or 2.0 compatible is indicated by its response to the AT+FCLASS=? command. To send this command to the modem and view its response you can use a Windows communications program such as HyperTerminal as detailed below:

• Start Windows HyperTerminal. Often a shortcut to HyperTerminal is available via Start, Programs, Accessories, Communications, HyperTerminal.
• Enter a brief name for this connection, e.g. "Modem Test", then click * OK *.
• On the "Connect to" dialog in the "Connect using" drop down list select the COM port to which your modem is connected, then click *OK*.
• On the "Port settings" dialog in the "Bits per second" drop down list select "19200", then click *OK*.
• You should now be at the main display, whatever you type will be sent directly to the selected COM port and therefore to the modem. Type "AT+FCLASS=?" (without the quotation marks) and then press ENTER.
• The modem should respond with a sequence of numbers, each number indicates a modem that the modem is compatible with as detailed below:

0 = Data compatible
1 or 1.0 = Class 1 compatible
2 = Class 2 compatible
2.0 = Class 2.0 compatible
8 = Voice compatible

• In HyperTerminal select the "File, Exit" menu to close HyperTerminal.