[hluska]

No, you can multiple sims in one phone, at least in the Apple world. iPhone has supported dual sim since 13 and eSIM forever. I don’t know about Android but I’m sure you can research that with a search like “{ your partner’s device mfg + model } and dual sim support”.

[tcrhelpforsms]

I'll investigate this, but I'm kind of surprised this use case would be even allowed? How does this wind up being different than a SIM cloning attack?

[hluska]

I don’t understand your question. One is an authorized user and one isn’t? That is the opposite of an attack.

[tcrhelpforsms]

Okay, let me explain it a different way. Much like TCR is in principle supposed to be about blocking phone spam, wouldn't it just be a matter of time before cell providers start cracking down on cloned SIMs with the intention of preventing criminal activity? Whether you cloned the SIM for legitimate use or not.