How do I use my iPhone for a password protected wi-fi?

I am trying to use my iphone 4 for a wireless network. I know how to set up the connection, but the problem is in addition to my router password I need to enter my connection username and password, too. What I mean is that I use 2 different connections from a single ISP with the same router and modem. So every time I want to connect to net with my laptop I enter my username and password. I do not want to change the way it works, but I am wondering if it is possible to access this network with my iPhone 4.

Any help is much appreciated. :)