What is the benefit?
You might be wondering why you need such application, since MMI code can be saved in your contact list. Yes, you can save MMI code in to contact list. But when it is in a contact list, you need to filter it out from the contact before sending it for getting balance info. Also it will increase the number of contacts you have in contact list, which will slow down your device when opening the contact list.
Why "Phone Calls" permission is required?
Application uses this permission in the application to have the ability to execute the MMI code.