Microsoft recently (like yesterday) released Microsoft PHP drivers for SQL Servers. Microsoft drivers 3.2,3.1, 3.0 and 2.0 for PHP makes it easy to connect to SQL Servers from PHP Applications.
Download the drivers from here:
This download has many drivers and you choose the version to match up with your PHP version.
I am having PHP 5.6 and will be using driver version 3.2
More details here: