@bluechards Tbh the biggest thing it does is store the key for the IMSI, which is used to authenticate with the carrier using challenge-response. But it can also store contacts, run Java apps, and do lots of other things.

But mainly they exist because of backwards compatibility. Telco is an insanely old and heavily regulated industry

@Kurt "What should we call this spider?"

"Well, it has long legs, so we should call it long legs"

"Hmmm, not kinky enough"