致命错误：调用未定义的函数mssql_connect（）PHP5.5

I am currently migrating a Drupal site for local development. One of the custom modules is throwing an error:

Fatal error: Call to undefined function mssql_connect()

I installed the MS SQL PHP Driver and included it in php.ini

extension=php_sqlsrv_55_ts.dll
extension=php_pdo_sqlsrv_55_ts.dll

However, the error still persists. How can I fix it? the dll's above are for the right version of PHP (5.5.31)