The Installing MSSQL for PHP page provides links to php_dblib.dll (i.e. FreeTDS) compiled for PHP versions up to 5.5.
PHP 5.5 will be unsupported from July 2016.
PHP 5.6 has support for security issues until December 2018.
If the DLL for PHP 5.6 could be provided this would cover PHP 5 systems for a further 2.5 years.