The paid services provided by third-party service providers include SMS/MMS, Unicom's letter, ringtone, super ringtone, voice mail and so on. The fees for these value-added services are set by service providers and charged to users, and Unicom operators will help to withhold mobile phone fees.
If the user has unclear value-added service fees, you can contact Unicom customer service to inquire and solve them. In order to avoid unnecessary expenses, it is recommended to check your mobile phone packages and services regularly to find out whether you have subscribed to unnecessary value-added services.