[neerajme]

@NetMage
the file that possibly needs modification is the the preferences.plist file in /private/var/preferences/Systemconfiguration

@Jeweibe
You said "Specifically I'm trying to add a proxy server setting under the settings for our custom APN. Obviously I can add the code in manually to a jailbroken phone, but I'd like a way to do it without jailbreaking all the phones around."

I want to do the same, however assuming it is a Jailbroken phone and one has access to the all the files and can change any file on the iphone. Which file would need to be changed and how?