The guestcall function is a very good idea in ClearSea, but in my opinion it has too much limitations.
Guests can call registered users, but registered users can not call guests. In daily use for example, there is the following problem:
I invite somebody as a guest and he try to call me some hours later. If I'm busy at this moment or even not in the office for a short time, I see a missed call, but can not call back. This is a dead end for the videoconference.
I would like to start a feature request to enhance the guest function.