案例库 · 软件与 IT · 技术决策 · 1984–1992
这条还没译成中文，下面是英文原文。
SMS traveled on the free space in the phone network's control channel
Designers put text in the signalling channel's spare capacity, so SMS cost almost nothing to carry and became universal.
Global System for Mobile Communications (GSM) · Friedhelm Hillebrand's GSM committee · network operators
那一手
GSM's designers wanted text messaging but wireless bandwidth was tight, and dedicated data paths were costly. The insight came from using an existing control radio channel that sat idle most of the time.
Friedhelm Hillebrand, chairing GSM's non-voice services committee, and colleagues settled on a 160-character limit, matching what fits on a postcard and what the free capacity could carry. The first message — 'merry christmas' — was sent by Neil Papworth on December 3, 1992.
为什么管用
- The signalling channel was mostly idle, so messages cost almost nothing extra to carry.
- It was built into GSM from the start, so every GSM phone could send and receive it with no upgrade.
- The 160-character limit fit the available bandwidth and the way people naturally wrote.
- Because it rode existing infrastructure, operators could offer it cheaply or free, driving adoption.
可以搬走什么
When a valuable service seems too expensive, find the under-used channel already in place and put the service there; the discovery is reuse, not new infrastructure.
后来呢
SMS became the default way to send text on mobile, generating tens of billions for operators and connecting billions of people. It grew into the foundation for mobile marketing, verification codes and app-less services, with annual text traffic reaching trillions of messages.
资料来源
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