The mobile phone beeps, saying that the other party has opened the music reminder service, and the short message informs the other party. What happened?

Hello, dear ~ It's my pleasure to answer your question. When you call, you will beep to say that the other party has opened the music reminder service, and notify the other party by SMS. What happened? The called party of 1 has set up a "call reminder" service, which is provided by the operator. After setting this service, when the called party is turned off, out of service area, etc. , and can't answer the phone (which can be set in the call reminder service), the incoming call will automatically go to the "call reminder" platform, which is equivalent to the called call transfer, so the caller hears the ring back tone given by the "call reminder" platform. The other party has turned on the call reminder. When the owner shuts down or the line is busy, a phone call cannot come in. Then the telecom operator will be at the owner's place.