Joke Collection Website - Blessing messages - Why does someone call and send a text message to a friend after his cell phone is turned off? What business? How did it happen?

Why does someone call and send a text message to a friend after his cell phone is turned off? What business? How did it happen?

Call to remind that 2 yuan has a monthly subscription. When the phone is turned off, the signal is not good, and people hang up, the calling number and time will be sent to your phone in the form of SMS. Some kinds of mobile phone card packages come with this service, which is free. For example, the Shenzhouxing music card comes with a free call reminder.