Why can Apple 5 mobile phone successfully send short messages to mobile phones that are stopped?

Friend, no matter what kind of mobile phone it is, if the other party stops working, you send a message to others, which will be temporarily stored on the server for a period of time, about three months from the date when the SIM card stops working. At this time, your mobile phone will show that the sending failed. If the other party's mobile phone is turned on again within 3 months, you can usually receive your message. Hope to adopt?