To place a call from the Start button

From NetMeeting 3.0 Help

To place a call from the Start button

Click Start, and then click Run.
In Open, type one of the following:
callto:computer name or IP address
callto:servername/e-mail address

For example:
callto:ils.microsoft.com/someone@microsoft.com

callto:e-mail address
To use the e-mail address only, you and the person you are calling must be logged on to the same server.

callto:phonenumber+type=phone+gateway=gatewayname