What does short message ussd mean?

Hello, the dialing method for using Unicom's trumpet service is 1. Call with a secondary number: Call → Enter the called number → Click the dial key → Select the secondary number to call out Note: The secondary number is displayed on the called party, and you can dial back directly; ? 2. Dial the secondary number: just dial the secondary number directly, and it will be automatically transferred to the main number. Note: 1, called: "calling number". At the same time, the service platform informs the called number which secondary number is called by USSD message. 2.USSD short message means that when the secondary number is called, the main number is notified by USSD short message, and the content of the short message is "Hello, dear user, X year, X month, X day, X number calls your trumpet X". Distinguish between minor numbers and major numbers; If the dialing method is correct, you still cannot dial normally. It is suggested that you can contact local manual customer service or directly provide your number to the local business hall for further verification. If you have any questions, please click /qA5yV for consultation.