From ModMyiFone - Wiki
AppTapp is hanging and not installing anything it seems?
Make sure iNdependence is quit, and then re-run AppTapp again. Also make sure you are choosing the correct version of firmware.
I have T-Mobile, and my EDGE isn't working. How do I get this set up?
Tmobile EDGE works fine. Make sure you have the Unlimited Data plan at $19.99. You will also need to set up your EDGE settings in the iPhone, which is in Settings>General>Network>EDGE. The APN is internet2.voicestream.com, and user and pass are blank. Some users have had success with wap.voicestream.com as the APN.
I have a carrier other than ATT/T-Mobile, and my EDGE isn't working. How do I get this set up?
Go to Settings>General>Network>EDGE and enter the APN and User/Pass. A very good list of all the settings can be found here.
Why am I having to re-activate my iPhone every time I put a new SIM in?
You didn't put the updated lockdownd file (mirror) in /usr/libexec/ on your iPhone. Do this now and you're good to go.
I am running a non-US carrier, and my voicemail won't work at all.
Follow this guide. This is NOT to get Visual Voicemail working, just to make it so when you hit the voicemail button it calls your voicemail.
Will a restore or an update re-lock my iPhone?
Yes.
How do I fix my number format from being xxx-xxx-xxxx to xx-xxx-xxxx or any other format?
Formatting is stored in:
/System/Library/Frameworks/AddressBookUI.framework/ABPhoneFormats.plist
Download this file from your phone. The file is stored in binary format -- Windows users can open it with XMLSpear (choose XMLSpear v2.30 stand alone for Windows) . Now open the ABPhoneFormats.plist file. Change the formatting under US to look like you want (if you find your region in the file, just copy from your region to the US and overwrite). When you are done changing formatting, save the file and upload it to the iphone in same directory you found it.