Iphone not connecting to my home wireless connection

[dgsammut]

Hi , i have been having issues with my phone connecting to my home wireless router. On the phone I am able to choose my network and connect but everytime i try to use a webpage it reverts back to the 3G. I have tried calling my carrier and my internet provided both of which could not help me. My laptops at home connect to the wireless without a problem however my iphone seems to get a different IP address and only the IP address & subnet mask are filled out where the router & DNS should also have inputted fields. I did speak to someone from my internet provider yesterday she seemed to fix the problem but whoever i spoke to today to configure another laptop changed everything she did and now the phone is not connecting again. I can't get anyone to help me so if anyone has tips or fixes to this problem please let me know, thanks.