[cubesnooper]

I find myself wishing more and more for a wifi‐only tablet in a phone form factor.

Sure, I recognize that I’m in the minority here, as someone who keeps his phone in airplane mode/wifi‐only mode all the time. But it doesn’t mean giving up much: most of my messaging (including replying to texts and checking voicemails) can be done from the browser, GPS navigation works fine without an internet connection (maps can be trivially preloaded), and when I desperately need internet access while driving I can pull into any Starbucks, McDonalds, or Walmart.

Mostly I do this for philosophical reasons (basically, purposely downgrading the importance of phone notifications relative to what activities I’m physically doing at a given time), but the security advantage of smaller attack surface is a benefit I hadn’t considered.

[MBCook]

It existed. It was called the iPod Touch. It was a full iPhone without a cellular modem.

It was discontinued, assumedly for low sales as more and more people gave their kids either iPads or hand me down iPhones instead of buying iOS touches like they used to.

[CameronNemo]

There was also the Samsung Galaxy Player. Discontinued long ago.

https://en.m.wikipedia.org/wiki/Samsung_Galaxy_Player

[BLKNSLVR]

Is a phone without a SIM card any equivalent, or just the fact it has the ability to have a SIM card means the attack surface is too big?

[chris37879]

If your goal is to reduce your attack surface, then yes, even a modem without a SIM is too much.

The modem in your phone isn't like a modem from the days of dialup, it's more like a cable modem. More often than not, the modem is its own entire microprocessor, ram, i/o, etc and then communicates with the device's CPU over a mixture of serial, i2c, spi, or other busses. For instance, in my Pinephone, the modem is a Qualcomm MDM9607, which is a single core arm cpu that has 256mb of ram and 256mb of nand on its package, it literally runs its own entire operating system (linux in its case) separate from what the CPU of the phone does.

This CPU can also have its own connection to the battery, which is how, for example, iPhones can remain 'findable' even when the phone's CPU is otherwise powered off and at rest. The modem sips at the little remaining power in the battery to power itself and the GPS chip to report the devices location.

As for 'removing the sim' that doesn't prevent the device from connecting to a network, just authenticating with it, typically. Your sim card is just a standard identifier and a little bit of storage that the modem can read and write to for things like storing contacts and SMS messages. All of which can be done in software as well (known as an eSIM these days).

Edit: Here's a link to the wiki page on the Pinephone's modem, just to give you an idea of what a cell phone's modem can be capable of, and keep in mind, it uses a rather old, outdated, and unpopular modem, other modems may have more features: https://wiki.pine64.org/wiki/PineModems

[vladvasiliu]

I don't think it's equivalent judging by the fact that you can still make emergency calls, which means it's able to talk to the network anyway. I remember than an older Samsung I had (GS3 IIRC) would show the signal level even withou a SIM installed.

Don't know what happens when you put it in airplane mode, though.

[rsync]

One caveat here ...

The baseband processor also performs real time audio and noise cancelling functions.

So while I have had some decent luck with VOIP and dialer apps that live solely in the application layer, voice quality and noise cancelling, etc., may not ever be as good as what the RTOS in the baseband can provide.

[MonaroVXR]

Do you have a source?