VoIP: SIP-over-TLS and sRTP: Jitsi Desktop

Formerly SIP Communicator, Jitsi, and now Jitsi Desktop.

Last tested version

2.11.5618 (after installing its keyring)
retested in May 2020 with 2.11.5624

Configuration

SIP-URI: Menu → File → Add new account → Network: SIP → SIP id (user@host)
SIP-over-TLS: enabled on default, thanks to DNS-NAPTR
SDES-sRTP: A) (button) Advanced, or later after account creation:
B) (menu) Tools → Options → Accounts:
(tab) Security → (expand) Advanced encryption → Protocols: SDES
… RTP/SAVP indication: Optional
which is RTP/SAVP + RTP/AVP

Software Bugs

SHA-2 Digest: ignores algorithm and picks all; therefore incompatible with Linphone
Dependencies: Ubuntu 16.04 LTS and Debian 9 work out of the box
Ubuntu 18.04 LTS requires …
Ubuntu 20.04 LTS and Debian 10 require …

back to the other (soft) phones.