You will still be able to receive calls from your cell provider, both while on the sip call and not.
- On the Jitsi download page there is a link to use their repo. Follow that link and install the repo using their directions. Trying to use the .deb file install just results in missing dependencies like jitsi keyring that you must get from their repo anyways.
- As of 2020 you must use java 8.
For Ubuntu 18.04 this is to be solved by install the default availble jdk8.
sudo apt install openjdk-8-jdk
sudo update-alternatives --config java
Select the correct version (java 8 from the list) and Jitsi will now start without error now.