MMI Code Messages on Android

MMI Code Messages on Android

What is an MMI Code? 
An MMI Code is a sequence of digits that is entered into your phone to make it perform some special action.
These codes start and end with a * or # so they don't get confused with phone numbers you might want to dial. They're usually only valid when you're not on a call, so if you key one in while connected to your cellphone company's IVR system they won't be recognized. Some MMI Codes are dealt with by your phone - for example, there's usually one you can key in to find out what software version your phone has installed.
Most MMI Codes are sent to your Cellphone company as they are used to turn features on and off (Like call forwarding, call waiting, etc).

What MMI Codes does YouMail use?
We use TWO (2) different codes.
The first (*004*17142043114*11#) is used to tell your cellphone company that it should send all of your unanswered calls to YouMail instead of your cellphone co's voicemail system.
Officially, we're enabling (turning on) the "Conditional Call Forward (Busy/No-Answer/Unavailable)" feature.
The second (##004#) is used to revert things back.
Officially, we're disabling (turning off) the "Conditional Call Forward (Busy/No-Answer/Unavailable)" feature.

Why does my phone say "MMI Code Failed"?
This will usually happen because your Cellphone company has decided that you aren't allowed to forward your calls. It could be because you are on a "plan" that doesn't have the forwarding feature (pre-pay/flex-pay plans usually restrict this feature). Unfortunately there is nothing we can do to 'bypass' this error - if you believe your plan should allow you to use this feature you will need to call your cellphone company and ask them to (a) let you control it from your phone, or (b) set the forwarding for you.
Note: If you go for option (b) make very sure that they only turn on "Conditional" forwarding (this only forwards Busy/No-Answer/Unavailable calls). Sometimes they'll accidentally turn on "Unconditional" forwarding (this forwards ALL calls!).

Note for T-Mobile Familiy-Plan users
It appears that when your phone is added to a family plan T-Mobile automatically disable your ability to use the Conditional Call Forward feature. The good news is that it seems to be more of a technical issue than a policy one. People have reported that they've been able to get YouMail working properly by following this procedure:

1.Call T-Mobile - from a different phone, as you'll need to mess with your cellphone while you're talking to T-Mobile.

2.Tell them that you are trying to get "Conditional Call Forwarding" working, but you are getting an error.

3.Get them to remove your phone from the family plan for 2 minutes,

4.While your phone isn't on the family plan, forward your phone using the option in the help menu, or by dialling the *004.... code above. It should work now.

5.Get them to put your phone back onto the family plan.