Dumb Question: PGPfone over Appletalk

Can someone tell me how to run PGPfone over Appletalk ? The documentation says that support has been added for this release, and there's a preferences box to check to use it, but there's no information I can find in the documentation on how to initiate a call over Appletalk.. it just says to enter a telephone number to dial. If I press 'Connect' without entering anything it hangs up the Mac. How do I tell it which machine I want to connect to ? Mark "Don't know much about Macs" Grant