[jacquesm]

SIM: Subscriber Identity Module almost says it all, on top of that a SIM can store your contacts (up to a certain number).

The SIM is what separates your identity from the hardware of the phone (which has its own identity called 'IMEI').

A 'software solution' would need a carrier, that carrier IS the SIM.

Another nice benefit of having the SIM device is that it makes it much harder to 'clone' a subscriber ID, something that would regularly happen in the days before the SIM card, note that the SIM was a development that came along with GSM, and that GSM was the first mobile phone standard resistant against cloning. It's one part of the 2FA (something that you have) that gives you access to the phone network (the other being the PIN code (something that you know) required to unlock the SIM).

[djhworld]

> on top of that a SIM can store your contacts (up to a certain number).

This presented a usability nightmare back in the days of feature phones, where if you didn't specifically say where to store contacts, it would often default to the phone's storage rather than SIM, or if you breached the number of contacts on a SIM you'd have overspill onto the phone memory (sometimes without realising)

This presented a lot of unnecessary confusion when it came to upgrading devices, or if you damaged your phone.

[WatchDog]

Well by the same token, sims offered a simple way to move contacts between devices, which was otherwise difficult to do without a pc and proprietary cables/software to export data from the phone.

[shavingspiders]

It still is an issue - carriers (at least in NZ) still ask you if you've backed up SIM contacts before switching the phone number to a new card.

[RandyRanderson]

When ppl mention a "software SIM" they mean the same basic chip embedded in the handset that you can switch with software. It has the same level of security as removable chips.

[rblatz]

I don't recall ever needing a PIN to unlock a SIM card.

[lmm]

The ability is there. Many people don't bother setting it.

[Aaargh20318]

Every SIM card I ever received came with a random pre-set PIN.