I just tested this and I can confirm that you are right, but rates are a bit higher than I expected for calls in Europe, maybe because server and everything else is based in United States.
Well it is mainly because the operator I use for the trunking of the calls is an American company. This in combination with the EU roaming regulations from 2016 which makes calls within EU cheap, which in turn made the telcos charge more from calls from outside the EU. The solution would be to use a European company to trunk the calls, and there is no reason why I can't have several and chose the one that is cheaper for each call. I have a European one too, but I haven't been able to get my PBX software to work with that one yet. I will investigate this, to my defence I'll say that I think configuring VoIP servers and getting stuff to interoperate is way more complicated than it should be...
I don't want to use anything like this that is connected with metamask wallet, so temporary sign-up would be just fine.
Maybe you can create something like Chipmixer website is using with their Session Token that is used to restore last session.
Alright! Temporary signup it will be... The session token is also a good idea.
I don't have anything against normal sign-up registration as long as I don't have to use email addresses or real phone numbers.
Hm, but if the signup doesn't use email or phone number, what would you be using? You mean signup with username and password (but no email)?