How to activate the SMS reminder function of missed calls of mobile cards?

Handling mode of monthly call reminder service: you can edit LDTX to send to 10086 for opening, and edit QXLDTX to send to 10086 for canceling, and 3 yuan/month. The opening and cancellation will take effect immediately, and the monthly fee will be charged normally. . . Call reminder service means that when the called user is turned off or out of service area, the call will be automatically transferred to the call reminder service platform. After the called user turns on the phone or enters the service area, the system will automatically send a short message containing the calling number and dialing time to the called user to prevent the called user from missing any incoming calls.