[mkvelidadon]

I downloaded ActiveMMS2G and downloaded the MobileConfig and I still don't have the celluar data network option available under network. I'm running 3.0 (7A341) on the 2g iPhone. Wassup???

[ThrowingChicken]

I've got the same problem.

[blkcadi]

Try this link.

[taitneddurian]

try to fix the APN

go here

I AM YOUR I.T. GUY Iphone 3G 3GS OS 3.0 can not find connect or activate cellular data network: how to remove cellular data network 3G

[BlackWolf]

you can manually activate that, but there are several steps involved. It's your decision if it's worth it, I will only give a quick description here, so it's not for total noobs:
1. Install Erica's Utilities from Cydia
2. SSH into your iphone and go to /private/var/mobile/Library/Carrier Bundle.bundle/
3. Execute "plutil -convert xml1 carrier.plist" (without the "s)
4. Open carrier.plist in a text editor
5. See if the file contains the following lines:

<key>AllowEDGEEditing</key>
<false/>

6.1. If it does, change the <false/> to <true/> save that and you are done
6.2 If it doesn't, go to the beginning of the file. It says something like:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>

below(!) that, enter this:

<key>AllowEDGEEditing</key>
<false/>

save it and you're done as well.