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"Missing Message Prompt" is a value-added service developed by Unicom for Unicom mobile users based on the communication housekeeper platform. User A selects the call-missing prompt service, and user B dials user A. When user A is not connected (including busy, power off and no signal), it will be transferred to the communication housekeeper platform, which will provide SMS reminder for user A. Additional functions include: number change notification, personalized first question, situational mode and voice mail.