Abstract: The invention relates to a method, arrangement and computer program product for temporarily preventing a certain function of a device. In the method according to the invention, a function of a portable device is temporarily blocked, so that in the device there is received a blocking key that blocks a certain function, and that the received blocking key is activated in the device in order to prevent a certain function. By means of the blocking key, there is temporarily blocked a given undesirable function of the device for the duration, until there is received an unblocking key, and by activating the unblocking key the blocked function is released to function normally.