How to Divert Calls on the iPhone with GSM Codes

Have you ever tried to forward incoming calls on your iPhone to another phone? Some weeks ago, when I was trying out the BabyFon application, I had to do divert all incoming calls. If you search through the iPhone's phone application to find a button which lets you divert calls, you will have no luck. Instead, you have to go to the settings application: Settings > Phone > Call Forwarding. In the menu you can enter a phone number where you want to have your calls forwarded to. In the same menu you can switch call forwarding on or off. There is also another way to forward calls. This is the solution I prefer as it comes in more handy when you need to use call forwarding on a day to day basis: you can use GSM codes and make convenient short cuts in your contacts database.


Do you wonder what GSM codes are? GSM is the abbreviation for Global System for Mobile Communications. This standard defines various codes with which you can control phones which implement this standard. For example, you can configure call forwarding and other similar options too. In this article we will look at call forwarding only. You can control lots of other features with GSM codes, which I will discuss in a later post.

These are the GSM codes of interest, if you need to divert calls on your phone:

  1. *21a phone number#  -- to register a phone number and activate the diversion of all calls to this number.
  2. *21# -- to activate divert all calls function (supposed you already have registered a phone number in the past).
  3. #21# -- to deactivate divert all calls.

You can enter these codes through the Phone's keypad. Just open the phone application and tap on the Keypad tab. Enter *21a phone number# to register a phone number to which you want to forward incoming calls. When you register a phone number, that will also activate call diversion. With the code #21# you can deactivate call diversion.

If you are like me you have every chance of forgetting to deactivate the forwarding function. Therefore, it might be a good idea to set an alarm in the clock application to remind you of turning off call diversion.

The next time you need to divert incoming calls, it is enough to enter the code *21#, as the number is already registered. If you need to divert to a different number you certainly can register a new number.

As I am not good in remembering GSM codes I have installed shortcuts in the address book. This is how you can do it: contactcalldivert

  • Open the contact to whom you want to divert the call to.
  • Tap on the Edit button and select Add new Phone.
  • Enter the GSM code together with the number you want to forward calls to (e.g. *2108150815#).
  • Press on the label beneath the phone field to add a custom field (Press Edit on the Label view, then select Add Custom Label).
  • Do the same steps once more to add a phone number which will deactivate the divert all calls function.

This is how you can use GSM codes to forward calls to another phone. Look through the list I have linked to for further useful GSM codes. For example, there are GSM codes with which you can hide your caller id when making phone calls. Check the Quick Tip category in the coming days. I will write another short post about the caller id soon.

Posted on CuteMachine.

Jo's Profile ImageWritten by Jo who lives and works in Frankfurt building digital doodah. Stalk him on Twitter.

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