1. For the sale model, the mobile operator provides SIM cards to the device company, and the device company produces the device and pays the connection fee to the mobile operator. The device company sells the smoke detector and service to the end customer who should pay the device and the service fee to the device vendor. 2. For the rental model, the mobile operator provides SIM cards to the device company, and the device company produces the device and sells it to the mobile operator, it also provides the service to the mobile operator. End customers will usually be regional governments and apartment or store owners, they only need to rent the smoke detectors from the mobile operators