What does briefing mean?

SMS means "Short Message Service".

Short Message Service (English: Short Message Service, abbreviation: SMS; sometimes also called messages, short messages, text messages, this service also has many common names in English such as SMSes, textmessages, messages or even texts and txts) is a type of mobile phone service.

The SMS service was first introduced on GSM system mobile phones, and now it can be used on almost any mobile phone system, such as 4G mobile phones.

SMS technology was first used in the European GSM system in 1991. GSM protocol 03.40 defines a point-to-point method, which is the most commonly used method by users.