Those are normally added to the notification Catigories list when we open a conversation, tap the 3 vertical dots in the upper right hand corner, and add a custom notification sound.
Check your conversation list for a message from 288402. If it's from someone you trust, carrier, isp, financial institution ect open it. Tap the 3 vertical dots in the upper right hand corner. Tap the notification sound option. The customization panel should have an option to reset the notification settings back to the defaults. If this doesn't remove the conversation from the main notification categories list delete the conversation.