First, choose a modem . Each modem and software combination has a different set of options, but most of these are to perform specialized functions. This can be used to identify the specific model you have. There are several ways to accomplish this, depending on the particular modem.
Some modems use both sets of commands.
Modem communications programs which identify your modem use these templates for that purpose. This may be selected by your software, in which case you won't have to worry about it. If you have an internal modem running at 14,400 baud or higher, you will get the best efficiency if you choose at least the next higher setting, and preferrably at least double the modem speed. For example if you have a 14,400 modem, select a port speed such as 19000 or 38800. If you have an external modem and do not have what is known as a 16550 UART, you may need to set the port speed to 9600 or slower.