Wireless Connection Issue

[BerkRider]

We have an apple wireless router that came with my sisters apple laptop. (I'm a long time PC user but an Apple newbie & my sister is a computer novice, to say the least.) I recently installed a Dynex router into the network so I could use my VoIP phone (which works fine) and now I cannot join my (sisters) wireless network with my iPhone 4. My iPhone seems to access other wireless networks just fine.
Both her's and my laptops can access the internet through the wireless connection. Only my iPhone can't.
I researched & tried the solutions on the Apple iPhone 4 support pages with no success.
I'm guessing it's some network settings I just don't know about.
Thanks in advance for any help you might provide this Apple/iPhone newbie.

P.S. & Off Topic: Our wireless connection is an unsecured network. Should we secure it & where's the best place to get the info 'd need to do it.

 

[DannyBoy]

What does your phone say when it tries to connect?

Yes, you should secure your network... Usually the manufacturer that made the router has instructions on how to access and setup the security features.

 

[BerkRider]

It shows the wireless connected icon at the top of the screen, but there's no internet, email, facebook, etc. access.
I also get an "Cannot Open Page" error." It says the server has stopped responding. (Using Safari)

I'll ask sis if she has the original documentation for her wireless router. Thanks.