At roaming partners you can only start and end charging with a SMATRICS customer card. Starting and ending using the app is not possible. At www.smatrics.com you can select your chosen tariff and receive your personal customer card.
At charging network operators which demand a fee, it depends whether there is an agreement between SMATRICS and the given network operator. A list of the current contracted partners and their costs can be found at www.smatrics.com/roaming-partner