The Extra Modem Commands option

Configure->InternetConfig->ExtraModem

This field allows extra commands to be sent to the modem or ISDN-TA before it attempts to connect to the Internet.

This is mainly intended for use with ISDN-TA's which often require switching to a specific mode, such as MLPPP or Dual Channel Bandwidth-On-demand, appropriate to the type of ISP account you are using.  Most analog modems should work 'out of the box' without any additional commands. Note that the "AT" which preceeds an "AT" command string should not be included in this field, only the commands themselves.

This field should be left blank if no extra commands are required.