This description is for manually creating an appimage which is a self contained binary with all dependencies and libraries to be able to run on any system.

https://github.com/AppImage/docs.appimage.org/blob/master/source/packaging-guide/manual.rst#creating-an-appimage-from-the-appdir

mkdir Linphone.AppDir
cd Linphone.AppDir
wget https://github.com/AppImage/AppImageKit/releases/download/continuous/AppRun-x86_64
mv AppRun-x86_64 AppRun
chmod 755 AppRun
mkdir -p Linphone.AppDir/lib
mkdir -p Linphone.AppDir/usr/bin

copy app binaries to usr/bin (extract deb and then included data.tar.xz)
chmod 755 usr/bin/*

check /usr path isn't hardcoded in the binaries, replace if necessary:
strings usr/bin/* | grep /usr
sed -i -e 's#/usr#././#g' usr/bin/*

extract/copy all required libraries
create app.desktop file to root
copy app.png file to root

cd ..

wget https://github.com/AppImage/AppImageKit/releases/download/continuous/appimagetool-x86_64.AppImage
chmod 755 appimagetool-x86_64.AppImage
./appimagetool-x86_64.AppImage Linphone.AppDir

#Note helper libraries might have hardcoded /usr as well, full search and patching via:
cd MyApp.AppDir/usr/
find . -type f -exec sed -i -e 's#/usr#././#g' {} \;
cd -