Okay, so in phpBB, OAuth service has already implemented as other authentication method for phpBB (in ACP > General > Authentication > Oauth), but phpbb only provides bitly, facebook, and google authentication by default ...
here's the picture :
so how can I add other service beside those three ?
You can't unless you have knowledge of or Oauth works and the PHP workflow. I wanted to extend the providers as well and a while ago I found an extension for phpBB called "BBoauth" by SiteSplat. Here's a screenshot of what I have enabled on my phpBB forum:
You can get a hold of a copy after you get the premium themes here: phpBB theme
It works great and the developer is top notch.