A calling method, device and system are disclosed. The calling method includes: obtaining, by a service platform, subscription information of a roaming prepaid subscriber, modifying and sending the modified subscription information to a visited mobile switching center (VMSC) of the roaming prepaid subscriber so that a call initiated by the roaming prepaid subscriber could be triggered to the service platform by the VMSC; receiving, by the service platform, the call to a called subscriber initiated by the roaming prepaid subscriber and triggered by the VMSC; and instructing, by the service platform, the VMSC to release the call and instructing a call connection device to connect the roaming prepaid subscriber to the called subscriber after determining from the call that the roaming prepaid subscriber has activated a callback service. User operation is simplified and user's experience is improved with the method, device and system in accordance with the embodiments of the invention.