During your Zoom conference, you may wish to pull in specific endpoints to participate. You can do this from the web interface as a host.
1) Sign into your conference and kick it off like usual.
2) Click the "Invite" button in your Zoom toolbar:
3) Click on the "Invite a Room System" category (1), then click on the "Call Out" tab (2). Make sure the radio button for H.323 is selected (3):
4) Choose the endpoint you'd like to dial from the drop-down list. You will need to contact your participants (preferably ahead of time) to know what unit to dial in.
5) Click the call button. This will ring the unit, and someone on the other end will need to answer it. If no one answers the call, you can try dialing it again later.