The action is dedicated of course only for the Czech customers of O2, both for fixed line and mobile users. It is possible to call to ordinary mobile or fixed lines, thus without the ones with a special charge. The principle is simple, it is sufficient to call to a special number, which should be itself for free, but it is not specified anywhere. After that you dial number, listen to one short (3 to 5 seconds) and one long (15 to 20 seconds) commercial and the call is connected as an ordinary call. It is possible to have just up to one minute call, fifteen seconds before the end a warning sounds and at the end the call is terminated. One can call up to ten times a week. After registration on the action web, see the link below, where the exact conditions can be found, it is possible to call up to twenty times a week. The sense of the registration is to target the commercials and thus information as salary, place, etc. must be filled in, which probably not everyone will like.