I followed the instructions on http://blogs.digium.com/2012/11/14/how-to-install-asterisk-11-on-ubuntu-12-4-lts/ and managed to install Asterisk 11 on Ubuntu 11.04 serve edition.
After installation I got "Illegal Instruction " error when I tried to start it using $ /usr/sbin/asterisk -cvvv command
After few mins of googling I got a suggestion to run the menuselect again and to remove the BUILD_NATIVE from Compiler Flags.
I done it and tried to make and install the source again but it failed with below error
The error says like fatal error: jitterbuf.h : No such file or directory
Also I am having a time skew error, kindly assist me to fix this