To use an AT command, establish a HyperTerminal connection from
the PC to the CTA 500dm. Type the letters AT followed by the
desired AT command. For instance, the AT&V0 command queries all
stored CTA 500dm parameters.

You can string several AT commands into a single entry (for
example, AT &V0 S26 I4). The individual AT commands within the
string do not have to be separated by spaces (AT&V0S26I4 provides
the same information as the separated string in the previous
example).