案例库 · 软件与 IT · 技术决策 · 1991
这条还没译成中文，下面是英文原文。
The GSM SIM made mobile identity portable and let roaming become normal.
The 1991 SIM card put the subscriber's identity on a removable smart card, so a number moved between phones and networks and roaming stopped being a swap.
Giesecke+Devrient · GSM · Elisa (Radiolinja)
那一手
GSM needed a way to identify a subscriber securely, but early approaches tied that identity to a specific handset. Instead the GSM project put it on a card.
Giesecke+Devrient delivered the world's first commercial SIM card in 1991 to the Finnish GSM operator Elisa, then known as Radiolinja. About the size of a credit card, it held the international mobile subscriber identity and its key, and a plug-in size could be broken out for smaller slots.
Because identity sat on a removable card, a number could move between phones and across networks; the account was in the card, not the device, and roaming became a billing detail rather than a hardware change.
为什么管用
- Identity on the card freed the number from a single handset
- A subscriber could switch phones or networks without a new contract
- The card carries the authentication secret, so networks trust the card
- Its size ran from a credit card down to micro and nano SIMs
可以搬走什么
Separate the portable identity from the device and the service becomes personal, not terminal-bound; that separation is what lets a standard travel across networks and vendors.
后来呢
The SIM became the anchor of global mobile telephony and the basis of roaming, shrinking over time and later becoming the embedded eSIM. The same removable-identity idea shaped separations behind many later standards.
资料来源
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