After reading from web and forum done successfull installation of OAuth (pecl package)
Doing pecl list - Installed packages, channel pecl.php.net:
Package Version State
oauth 1.0.0 stable
Also updated the php.ini file at /etc/php5/apache2/php.ini
with extension=oauth.so
But nothing shown at Phpinfo and also getting error PHP Fatal error: Class 'OAuth' not found
If it's mod_php, you need to restart the Apache server so it picks it up.
sudo apache2ctl restart
Otherwise try loading the module manually with dl() first, to see if it works at all.