SMSSMS is the acronym for Short Message Service.
The original standard for sending text-based messages via mobile devices. A single text message was limited to 160 characters including spaces. SMS was designed to fit within other signaling protocols, which is why SMS message length is limited to 160 7-bit characters, i.e., 1120 bits, or 140 bytes. If a user sends more than 160 characters, it could be sent in up to 6 parts total number of 918 characters in the linked message.