How to check whether Unicom number has opened the missed call SMS reminder function?

Hello, the missed call SMS function is usually called "incoming message treasure" or "missed message treasure", which is a value-added service. When the phone is turned on, the phone receives an incoming call in the service blind area or in the off state, and you can receive a short message reminder after the phone is turned on. You can only use this function after applying for opening. You can recall whether this function is enabled or not, and whether this function fee has been charged in the phone bill. The mobile phone can not be used until it is officially charged. It is suggested to call the local customer service hotline 100 10, and the manual customer service will check whether it is open.