Can php be configured to browse through a proxy?

There is some information about configuring php to use a proxy when connecting to external urls. According to some sources the proper setup option is by using the stream-context-set-default function ( http://www.php.net/manual/en/function.stream-context-set-default.php) Still I have not been able to find any reference about if it can be set on php.ini (so all the instances of php use it) Also there is this bug that has been assigned since 2010 and still have not changed (29280) https://bugs.php.net/bug.php?id=29280 Any information about this will be well received. Thanks, Joan