I would actually be grateful if someone who has more time checked how free and
nonfree versions of Linphone talk to each other.
Yes, some experimentation would be appropriate.
Meanwhile, for common knowledge, this is how apps like Linphone work, very
roughly:
0. The interlocutor is found in a remote SIP directory.
1. A direct SIP connection is negotiated and established.
2. Your voice is digitalized with VoIP and stored in memory.
3. RTP is used to safely rely the stored data back and forth.
The VoIP interlocutor will be able to capture your IP and version during points
0 and 1.
As a consequence, in most circumstances it would also be possible to implement
a warning about communication with non-libre endpoints before point 2 starts.
❔ Would you consider the project responsible if the user of the libre version
unknowingly includes a non-free client in a conversation?
❔ What could be the ethical and safety implications of not warning the free
user that this is happening? (so the free user can at least prevent or close
the conversation)
I am open to different outcomes, but it just occurred to me that we don't see
an issue with free e-mail clients being able to send/receive e-mails from
nonfree e-mail clients, do we?
...but the web email archives kept by GNU will still store and publicly display
the name of the e-mail client used by each thread participant. Amongst the many
email headers, keeping and showing this one in particular. Perhaps, while as
you say us three don't see an issue (at least in asynchronous protocols), other
F/LOSS lovers may not be so open minded. 🤨
Privacy-side (which I'm sure won't be an issue here, but it is still worth
noting) the nature and sensitivity of the information exchanged via email is
much different.
With emails, all users are well-aware of the privacy risks, because the
presence of at least two servers involved in each asynchronous communication is
made obvious by the clients and all emails are saved by default, so the
information is known to be permanent. The same cannot be said for calls and
videocalls, which are naturally considered ephemeral, fully private and
personal. Now we have AI and we all know its dangers: exfiltrating company or
family meetings, affairs, negotiations and other sensitive interactions could
be very bad, especially because anything can happen during synchronous
real-time communications, even unwanted things that should remain OTR.
On the side of ethics, a person could legitimately decide that they have the desire or even
necessity (depending on the walk of life they're currently in) to mainly or only interact with apps
which are free and hold no surprises in their codebases. The word "free/libre" can
provide a sense of assurance and trust which should be well-founded. If their interlocutor says
"I'm using Linphone", the logical expectation is that a libre client is executed on both
sides, no strings attatched.😉
~Lorenzo