> Message delivery is "best effort", so there are no guarantees that a message will actually be delivered to its recipient, but delay or complete loss of a mess

> Message delivery is "best effort", so there are no guarantees that a message will actually be delivered to its recipient, but delay or complete loss of a message is uncommon, typically affecting less than 5 percent of messages. https://en.wikipedia.org/wiki/SMS https://en.wikipedia.org/wiki/SMS Oliver, Earl, Design and Implementation of a Short Message Service Data Channel for Mobile Systems https://cs.uwaterloo.ca/research/tr/2007/CS-2007-42.pdf https://cs.uwaterloo.ca/research/tr/2007/CS-2007-42.pdf