Call "waiting" is a service that all new phone lines have turned on by default and that existing phone lines can have turned on as an option. What it does is send a series of pips to advise you when a second call is on the line.

The problem with using a modem and having call waiting switch on is that the little pips it sends will cause your modem to drop the connection.

So if using a modem make sure call waiting is turned off.

#43# will turn it OFF

*43# will turn it ON

*#43# will tell you if it is ON or OFF