How can there be three numbers in SMS synchronization management?

Because of the community cornet, SMS synchronization management has three numbers. According to the query, all three mobile phone numbers can receive information synchronously by managing a short message, which belongs to the community short number. According to the setting of the Bangtong group sending platform, if two cards have been inserted into Xiaomi's mobile phone, then another card will be inserted, and one Xiaomi account will be used for three mobile phone numbers. Synchronization management refers to whether the SMS records of cards that have been inserted but taken out of Xiaomi mobile phone are synchronized to Xiaomi cloud for backup.