To change tariff plan "Megaphone", you have to first determine a desired rate and find its description on the official website – In the top menu of the website you need to choose your region. Once the region is selected, the page will reload and the main menu will need to choose the section "Tariffs".
Tariffs are classified and divided into groups. Select the desired group (for example, For communication with subscribers of any operators") and then you are interested in the tariff. If the transition at this rate can not be closed, in the brief information about the rate on the last lines of the description you will see "USSD-command to change tariff plan". Code, located opposite, is the code to move to the selected tariff.
Now to move to a specific tariff plan, dial the code on your phone, press the call button and follow the instructions. You may get a reply SMS which will ask you to dial the code again or send message to confirm switching to the new tariff.