How come there aren't aren't any global multi-platform alternatives? Or are there?
Google hangouts is so atrocious that it cannot count.
The Skype people actually came from Kazaa, so they had a lot of experience with sending peer data across corporate / educational firewalls.
WebRTC is trying to generalize the technology, but it's new.
(disclaimer: I'm an engineer at appear.in)
> The appear.in team currently consists of 14 people, and operates as an independent startup within the incubator environment of Telenor Digital.
That's not cheap, and it doesn't sound like it's just a side-project to raise awareness for the parent company or something like that.
Point about single-server downtime still stands, of course.
So Skype is more complex than you'd guess.
Your best bet is something using WebRTC.
This implies that there cannot be a peer-to-peer setup since both peers-to-be can only go out and never connect to the other. And hence there is a server in between the two chat partners.
https://telegram.org/faq#q-can-i-make-calls-or-video-calls-v...
BTW there is an abundance of VoIP services these days, from Facebook calls to Whatsapp to Google Hangouts to Viber to Fring.
We rely on slack; we had multiple short outages last week. In slack terms, only a small number of teams were affected, but for us, that meant the whole company.
To be fair, the outages were short, and slack kept us in the loop. But the wider point is that such outages are possible with any SPOF, and if you work in a remote team, you should have a contingency plan to know which of those many alternatives you'll coordinate on when your primary service is down.