silviapfeiffer

We run a video consultation platform (https://www.coviu.com/) and you can activate a stripe integration to create appointment bookings with associated stripe payments (activate the "Client Payments" addon from https://coviu.com/addons). People can't enter the video call without having paid. You might want to check out if that solves your problem.

Just to be complete: rtc.io has a signalling server at https://github.com/rtc-io/rtc-switchboard . Choice of library is up to you. :-)

Before you can "ring" somebody in their browser, their presence has to get established first. So, they need to have signalled their presence to a signalling server first. That can happen via loading a specific URL, or being logged in to a specific Website. It's not possible to just magically know that they are around without them announcing it.

What does the "arbitrary service" provide? Is it a video conference, audio conference, or data channel end point?