One system. Two ways to connect.
If they're near you, they can hear you. Next time there's a traffic jam, let someone in your car talk to people up ahead and find out what's happening. Talk to your neighbors as you take an afternoon walk, or find out what's happening on campus. No registration, no social network. Just turn it on and talk.
Provision a private channel. Get a claim code you can pass to your friends. They just enter the code, and they're in the channel. Private channels can be provisioned with or without a geographic restriction, so you can keep in touch anywhere you go.