To use a gatekeeper to place calls

From NetMeeting 3.0 Help

To use a gatekeeper to place calls

On the Tools menu, click Options.
On the General tab, click Advanced Calling.
In the Advanced Calling Options dialog box, click Use a gatekeeper to place calls.
In Gatekeeper, type the computer name or IP address of the gatekeeper computer. If you are calling a conferencing server, type the name of the MCU instead.

Notes

If you log on to your organization's gatekeeper using your e-mail address, click Log on using my account name. Otherwise, click Log on using my phone number and type your phone number in the box.
If you don't know the computer name or IP address of the gatekeeper, contact your network administrator.
If you place calls using a gatekeeper, directory servers do not appear in the Directory list.