+ + gsm codec (gsm source package or libgsm-dev or gsm-devel) (optional)
+ + libreadline (optional: for convenient command line in linphonec)
+ + libsoup (optional: for wizard - account creation assistant)
+ + libsqlite3 (optional : for a local history of messages)
+ + if you want uPnP support (optional):
+ - libupnp (version 1.6 branch (not patched with 18-url-upnpstrings.patch))
+
+ + Install srtp (optional) for call encryption :
+ $ git clone git://git.linphone.org/srtp.git
+ $ cd srtp && autoconf && ./configure && make
+ $ sudo make install
+
+ + Install zrtpcpp (optional), for unbreakable call encryption
+ $ sudo apt-get install cmake libssl-dev
+ $ git clone git://git.linphone.org/zrtpcpp.git
+ $ cd zrtpcpp && cmake -Denable-ccrtp=false . && make
+ $ sudo make install
+