How to unlock iphone for baseband 6.15

[Loverface]

I have an iPhone 3g and i think my wifi has been broken due to the baseband upgrade,it do searches my wifi for some seconds but then quits,and now i think i have to unlock my phone which is on 3.1.3 baseband 6.15.00.I don't have any idea hoe to do this,is there any one who can help me out with this? any help regarding this will be highly appreciated.

[Ceesar]

Such problems occur if you have not successfully downgraded your baseband but if you find your wifi is greyed out or it is just crashed then what all you can do is re-jailbreak with custom firmware and then unlocking it with ultrasn0w but If you still find 6.15 baseband then just restore it with custom firmware.Ihope jailbreaking will solve your problem else you have to surely try custom firmware.

[Crespin]

If you are sure that the wifi is grayed out then you have to reflow the chip but if you think that the wifi is there but its not able to catch any network then your antenna would have been damaged,you have to get a new antenna you will find a cheap one at ebay, but keep in mind that the reflow method is kind of a risky process, so try to get a good information on it or Google it out.