I am building Linphone application for android. I am working in Ubuntu 11.04 OS.
I Followed the steps given in README file:
If you still need an answer...
In your ubuntu 11.04, open your terminal, make sure you are the root user
* make sure you have done this: "git clone git://git.linphone.org/linphone-android.git --recursive" //*the --recursive part is very important
* then do this: apt-get install autoconf automake libtool pkg-config
* go to your project root: cd/home/user/project //wherver your project is
* in your project root: export PATH=/home/user/android-ndk:$PATH //wherever your android-ndk is stored in
* then run ./prepare_sources.sh //in your project root still
* after that do this: /home/user/android-ndk/ndk-build // in your project root too