How to use libphonenumber for php

How to use libphonenumber for php

I've attempted to run libphonenumber for PHP as per this question but have
been unable to get it running. All I get is the following, and I have got
Composer installed. I'd greatly appreciate any direction on this.
My output:
Warning: require(/var/www/phone/libphonenumber/vendor/autoload.php):
failed to open stream: No such file or directory in
/var/www/phone/libphonenumber/index.php on line 2
Fatal error: require(): Failed opening required
'/var/www/phone/libphonenumber/vendor/autoload.php'
(include_path='.:/usr/share/php:/usr/share/php/PEAR:/var/www/cakephp/lib')
in /var/www/phone/libphonenumber/index.php on line 2