How does Unicom Gold Bank send short messages with a supplementary card?

Unicom gold number is to assign a phone number or digital ID number to the user's mobile phone. The original number of the user is the main number, and the new number is the auxiliary number. You don't need to change your mobile phone or number, so you can dial the double number. Users can choose the number displayed when calling out, which effectively protects the privacy of personal communication. More value-added services: teleconference (within 16), voice mail, online status setting of extension number and other functions. However, it is only used for telephone voice, and the short message function has not been opened yet.