Possibly https://ring.cx/
No first hand experience though but would seem to fit the bill.
- [Trisquel-users] Free and Open Google Hangouts/ Sky... davidpgil
- Re: [Trisquel-users] Free and Open Google Hang... Deys
- Re: [Trisquel-users] Free and Open Google Hang... davebright
- Re: [Trisquel-users] Free and Open Google Hang... davidpgil
- Re: [Trisquel-users] Free and Open Google Hang... t8mf4nu6lizp
- Re: [Trisquel-users] Free and Open Google ... Adonay Felipe Nogueira
- [Trisquel-users] Re : Free and Open Google Han... lcerf
- Re: [Trisquel-users] Free and Open Google Hang... davidpgil
- Re: [Trisquel-users] Free and Open Google Hang... davidpgil
- Re: [Trisquel-users] Free and Open Google ... megver83
- Re: [Trisquel-users] Free and Open Goo... greatgnu
- Re: [Trisquel-users] Free and Open... davidvargas1
- Re: [Trisquel-users] Free and... megver83
