A free program for Android, by SKTelecom.

This app allows you to manage your T call history and set additional services, such as add-on messages and caller tunes.

How to Use

The first thing you need to do is install the app and set a password.

If you have a valid username and password, you will be able to log in.

The login screen will show you your account status.

You will be able to manage your account settings.

After that, you will be able to manage the service settings.

How to Set Additional Services

There is a section for additional services.

You will be able to set an add-on message and caller tune.