alt Hacker NewsAt age ~11, I sent a MSPaint design of a phone with two SIM cards that you could switch between physically on a phone.
I sent it to Nokia over email :-D. They didn't respond.
Dual SIM phones apparently became a thing that same year: https://en.wikipedia.org/wiki/Dual_SIM#:~:text=The%20first%2... Not originally by Nokia, though.
Back when SIM cards were relatively new (and credit-card sized) ca 1997 or so, the vision was that you would plug your SIM card into a landline phone to be able to make/receive calls there. I was working for Motorola at the time and I remember coming up with a couple ideas that I never shared with anyone because I didn’t know who/how.
The first was essentially the iPhone but with a palm pilot type touch screen, the other was a PCMCIA card (which were also much larger back then) that you could put your SIM card into and plug into your laptop to be able to make calls or send/receive faxes on the computer.