We have seen forum reports and posted comments that there are some who have issues with their Internet on the iPhone after jailbreaking with Geohot's blackra1n (Well, you may have the same issues after using Pwnage Tool to jailbreak and unlock).
The issues focus on no Internet connectivity (no 3G network or EDGE network connection) as well as Wi-Fi connection problems.
If you have these network problems, reset your network settings to see if this solves your problem. You can do this by:
1. Go to Settings > General > Reset > Reset Network Settings.
2. Reboot your iPhone.
Are you having problems with connecting to YouTube or any issue with push notifications? This is due to the hackivation in blackra1n.
If you are having hacktivation issues:
1. Add http://cydia.iphoneil.net to your sources in Cydia.
2. Search for an app called "Push Fix" and install it.
3. Reboot your iPhone.
Our recommendations for starting from scratch (with a newly installed iPhone) is to jailbreak your iPhone using PwnageTool. You can find our handy guide to this here: How to Jailbreak iPhone 3.0 Using PwnageTool 3.0.
If you need to unlock your phone, unlock it with Blacksn0w if you are on the 05.11.07 baseband. Our guide to using Blacksn0w is here: 1… 2… 3… Blackra1n Unlock is Available Via Cydia.
If your baseband has NOT BEEN UPGRADED to the 05.11.07 baseband, then use ultrasn0w to unlock your phone. Our guide to unlocking with ultrasn0w is here: How to Unlock iPhone 3G and 3Gs Using Ultrasn0w.