The 160-character limit was a clever way to use unused digital space
Long before WhatsApp, SMS revolutionized communication by hijacking the 'empty' signaling paths of cellular networks. Originally designed for carrier alerts rather than chatting, this ingenious use of leftover bandwidth turned a technical byproduct into a global social phenomenon that once connected 3.5 billion people.
In the mid-1980s, engineers Friedhelm Hillebrand and Bernard Ghillebaert developed the concept for SMS as part of the Franco-German GSM cooperation. The technical challenge was to transmit messages without disrupting telephone traffic. Their solution was to utilize the signaling paths—the digital 'lanes' used to control calls—during periods when no signaling traffic existed. By using these unused resources, the system could transport messages at a minimal cost to the operator.
To ensure messages fit within existing signaling formats, the length had to be strictly constrained. Hillebrand, drawing on his observations of the typical lengths of Telex and postcard messages, argued that 160 characters would be sufficient for most brief communications. This constraint led to the creation of 'SMS language,' a phenomenon where users shortened words to stay within the limit. While the payload is technically limited to 140 bytes by the SS7 protocol, the use of a 7-bit alphabet allows for the iconic 160-character limit.
The technology's impact was massive. By the end of 2010, SMS was the most widely used data application, reaching an estimated 3.5 billion active users, or roughly 80% of all mobile subscribers. It evolved from a simple tool for carrier alerts into a global industry, earning $114.6 billion in 2010 alone. While modern IP-based services like WhatsApp now challenge its dominance, SMS remains a vital utility for two-factor authentication, mobile banking, and even emergency broadcasts.
The first true test of the service occurred on 3 December 1992, when engineer Neil Papworth sent a 'Merry Christmas' message from a computer to a colleague's Orbitel 901 handset. Since then, the service has transitioned from early 1990s digital networks to present-day 5G, with the industry now moving toward Rich Communication Services (RCS) as a potential open-standard successor.
Source: SMS
