I need a sip client to make calls from my laptop. I have an account from voipinfocenter. What is the best SIP client with a nice UI?
Swarfendor always recommended Jitsi.
Jitsi meet is open-source video conferencing alternative to Zoom. https://jitsi.org
I don't know about installing it on Linux though.
Signal is open-source messenger/calls/video calls alternative to WhatsApp, Skype etc. https://signal.org/
Signal Linux debian install here https://signal.org/download/linux/
Signal Desktop can also be found in the Zorin Software Store (Warning: This listing is a Snap app)