Open Phone and Modem Options in Control Panel.
On the Modems tab, click the modem that you want to configure, and then click Properties.
On the Modem tab, under Speaker volume, move the slider to the left or right to adjust the volume.
Note that these dialers usually make the fist call, they don't dial out whilst you are on line.
Put 'dialers' in Search for various threads to get rid.