> From a UX perspective the simcard is a pretty weak solution.

Actually from a UX perspective sim cards are a pretty strong solution because there is a clear and simple 1:1 mapping between a physical object and a carrier. That's as simple an UX as can be: if I want to use carrier A I use SIM A, if I want to use carrier B I use SIM B.

> For a starter, why do I have to reboot my phone to switch carriers?

I don't know, do you? I don't. I just take out the iPhone's SIM tray, replace the SIM and put the tray back in.

> Actually from a UX perspective sim cards are a pretty strong solution because there is a clear and simple 1:1 mapping between a physical object and a carrier. That's as simple an UX as can be: if I want to use carrier A I use SIM A, if I want to use carrier B I use SIM B.

That must be why it's so common and popular to use physical tokens for the address list too. I really live to sift through the little plastic cards I keep in my pant pocket (careful not to lose one!) to find John Doe, insert it into the phone and reboot, just to make a phone call.

Or not.

Your nonalogy makes no sense whatsoever:

* Addresses don't significantly impact the phone's behavior (and its costs), current ISP does

* As I noted, you might want to get out more, phones don't need to reboot when changing SIM

* Considering the number of people who criticize iPhones for not having a µSD slot, physical tokens do indeed seem trendy in crowds which need them

Actually the analogy is good. Having a physical token is very messy from a UX perspective. A menu is just as easy: If i want to use carrier A, i select carrier A in the menu, if i want to use carrier B, i select carrier B in the menu. This is what i do every day with my WiFi-network on my laptop....

Your µSD-comparison is what doesn't make sense. An SD-card can contain several gigabytes of data that would take hours to transfer to the phone. A SIM-card probably has a small key on maybe a few kilobytes that can be transfered and stored by any more or less modern communication-method, wired or not, within a few seconds.

But from a security perspective SIM is a much better solution because once you make the key transferable by software it will be much easier to steal an identity.

> Your nonalogy makes no sense whatsoever:

I'll agree it has several flaws. Still.

> Addresses don't significantly impact the phone's behavior (and its costs)

That would be a reason to keep the interface a physical token? Elaborate, please.

> phones don't need to reboot when changing SIM

The stupidly designed ones (with the sim behind the battery) does, but I see your point.

> people who criticize iPhones for not having a µSD slot

I was under the impression they miss the ease of data transfer and cheap storage space, not the act of changing the card to access other data. Please elaborate.

Business cards are hardly ideal. But, knowing that someone now has your correct contact information, because you just handed it to them is worth something. The problems only really show up when you want to keep several addresses at the same time and for most people that's rarely an issue with SIM cards.

You don't have to reboot your phone (e.g. the iPhone doesn't need a reboot when switching SIM cards). But a lot of phones hide the SIM under the battery, and your phone won't keep running with its battery off.