Apple IPhone “Call Forwarding Active” message on all outgoing calls

I was using my IPhone with Spice. Recently I switched my service provider to Docomo. When I switched to Docomo I noticed a message displayed on my IPhone “Call Forwarding Active” on every outgoing calls. It was not a problem functionally and the message used to go away as soon as the call got connected or by pressing "Dismiss". My phone was working fine otherwise.

However when the message was displayed on the phone one could not perform any operation on the phone without clicking on the “Dismiss” button.
This was really annoying. It was not a bug as I tried with Spice, Airtel sim cards and there was no such message not only that this message was getting displayed on Nokia phone as well when I used Docomo sim. This was certainly not a problem with the unlocked IPhone as I thought initially.

This made me think that this might be a configuration issue. Googled and found the following solution.
Use Cydia to install OpenSSH. Use WinSCP or any other utility to connect to your IPhone.
Browse to the following directory
/System/Library/Carrier Bundles/Unknown.bundle
Look for the file carrier.plist. Before doing any other operation make sure that you take a back up of the same.
Copy the file to the local computer.
You can use “Plist editor” to edit the file. You can get one for windows here.
Change the key for “ShowCallForwarding” to false.
Put the edited carrier.plist file back to the IPhone.
Restart you IPhone and annoying message is gone. All your call forwarding setting will be retained just the message is gone.

The above process worked for my IPhone which was unlocked using blackra1n and running Firmware 3.1.2.

Enjoy!!!