Server :: How To Www-data Chown A File

I have a php script that creats some files and moves them into certain directories. When the files are created, the ownership is www-data:www-dataWhen they are moved to the appropriate directories the maintain that. But, I need the files' ownership to be changed to asterisk:asteriskHowever, www-data doesn't have permissions to do this. I don't want to run a cron as root that does this (I'm already doing that). I really wish there was a way for my files to be created via my php script and in that same file do something like:
system("chown asterisk:asterisk /home/test/test.call");