I write to report some success attempting to connect the L5 as a SIP phone to my Fritz!Box. It is only a very brief test.
Basically, the configuration starts on side of the Fritz!Box, where a new phone device has to be configured by (freely) adding a username and password. This username/password can then be added as a new voip account on the L5.
Initially, the registration failed for a while. I may or may not have failed to enter the same configuration on both side. After some tries, though, the registration succeeded finally and appears to be stable in that it can now be reliably registered and unregistered.
I tried a single incoming call, which (among other devices) came in on the L5. When i took up, the connection got established and audio worked properly at least in one direction (to the L5 speaker). I called back using “0123...@192.168.0.1” where “192.168.0.1” is the ip addr of the Fritz!Box and “0123…” is a regular telephone number. And the other telephone was actually ringing. It also work well with the “internal” telephone numbers provided by the Fritz!Box., which allows to call the only the L5.
Unfortunately, no audio appears to be send from the L5, yet. The mic switched on and i saw the L5’s mic actually getting audio in the sound config dialog. The Fritz!Box shows no codec and no data in one of the directions of the connection.