Can I use CoreTelephony in my iPhone app without it being rejected from the AppStore?
Situation has changed, some parts of CoreTelephony are
Available in iOS 4.0 and later.
Check for details:
http://developer.apple.com/library/ios/#documentation/NetworkingInternet/Reference/CoreTelephonyFrameworkReference/_index.html#//apple_ref/doc/uid/TP40009603