iPhone in my pocket forgets its a phone

May 6, 2011 11:20 AM

Why does my iPhone forget it has a SIM card when I keep it in my pocket?

Strange phenomenon. My iPhone 3G often forgets that it has a SIM card. That is, a "No SIM card installed" box pops up in the middle of the screen, and I've got no phone/3G service. Every once in a while it's "Invalid SIM," but usually "no SIM." Powering down the phone and turning it on again fixes the problem, though about 1 in 10 times I need to power down and up two or three times.

I have noticed that this ONLY happens when I keep the phone in my pocket (though it doesn't happen every time I keep the phone in my pocket.) I take the phone out, and "No SIM."

Does anyone have any idea what's causing this? Or whether there's an easy fix other than keeping the phone in my bag all the time?

posted by escabeche to technology (6 answers total)

It sounds like the connectivity between your sim card and your phone is screwed up. This might be something that the Genius Bar could fix for you (or at least run a diagnostic on to identify a full-on issue).
posted by patronuscharms at 11:26 AM on May 6, 2011

Probably a hardware failure, but still possible that it's a software thing, especially since power cycling the device temporarily fixes the issue.

Restore as new (not from backup), and if that doesn't fix the issue, you know it's a hardware problem. As for hardware, it could be a faulty SIM, a faulty SIM tray (just swap out with a different one, 10 seconds), of faulty contacts inside the phone (requires repair/replacement).

You lose everything with restoring as new, so if you go that route make sure you sync/transfer all your data to the computer. Don't just rely on the phone backing up (since you're not going to use that backup file after the restore).
posted by spikeleemajortomdickandharryconnickjrmints at 11:30 AM on May 6, 2011

Specifics on how to isolate hardware issue from software issue.
posted by spikeleemajortomdickandharryconnickjrmints at 11:32 AM on May 6, 2011

Hey, I have this same problem! Mine is a jailbroken 3G.

I'm certain it's a mechanical issue. It's persisted across several restores.

In my case, it only happens when I carry the phone in my back pocket. No other kind of pocket has triggered it. Only back pants pocket, and I believe sitting or crouching is a necessary trigger.

My assumption has been that back pocket + sitting causes some flex that disengages the SIM contacts temporarily and the phone gets confused. Pulling and reseating the SIM tray does nothing; only a power-cycle.

I've found no solution other than "Don't put the phone in your back pocket, chaz."
posted by chazlarson at 11:53 AM on May 6, 2011

It does sound like the contacts between the SIM and the phone are loose and the slight pressure and flexing in your pocket are causing the phone to think the SIM is missing.

Have you tried ejecting the SIM and reseating it? I had a 3G that exhibited similar activity and just doing that fixed it. If it doesn't immediately correct the problem you can squirt a blast of air into the open SIM slot to remove and dust. To eject the SIM, use that little tool that came in the box or a tiny paperclip. If it still isn't working, you might swing by an AT&T store and tell them you need a new SIM card and they'll transfer your account over to that one. If that doesn't work, you'll probably have to get a new phone ($) or not carry the phone in your pocket.
posted by birdherder at 11:56 AM on May 6, 2011

What about trying to make the SIM card slightly thicker to ensure tighter contact? Like put a couple layers of tape on the non-contact side, then reinstall. It's easy and cheap to try, and reversible.
posted by jeb at 12:44 PM on May 6, 2011