"SIM card invalid" message, phone restarts fixes it only for a few minutes - iPhone 6s

[goldfish]

I got my mom set up with Public Mobile around 6 months ago and everything has been good up until yesterday, when she got a "SIM card invalid" message on the top left of her screen and she wouldn't be able to call anymore. When she restarts her phone (sometimes a couple times), the message would go away, but return after a variable amount of time (sometimes a few minutes, sometimes a couple of hours).

Has anyone else run into this issue and was able to fix it?  Thanks!

[GinYVR]

@goldfishYou can always get her to go to an Apple Store if there is one near her.. Service wihtout needing a work order is always free.. they are always kind and patient to seniors.

[goldfish]

All of the comment were good suggestions - unfortunately, my mom lives alone across the country with quite a language (and technology) barrier so it's not super easy to either teach her how to reseat the sim, or find someone to test the sim in a different phone for. She'll find someone to help her try the first three suggestions (reseat/test the sim on a different phone, gently clean the SIM) out tomorrow, and I'll update the thread if any of the suggestions fixed the issue. Thank you all!

[Korth]

Try an electrical contact cleaner on the SIM card contacts, they eventually accumulate an "invisible" layer of galvanic corrosion which inhibits proper electrical contact.  Also clean the device-side contacts if you're able to reach them without dripping liquid/debris into the device.

Isopropyl (99%, without perfumes/additives) is a good enough solvent (if you're careful to keep the liquid and fumes away from soft plastics).  Soft pink rubber pencil erasers also work surprisingly well (but should be used sparingly because they rub off some of the microns-thick gold surface).  DeoxIT or Stabilant-22 are best if you have any, but they usually cost more than the SIM card itself.

[kselmak]

Would you be able test the sim in different phone?

[ChuckYeah]

No, but have you removed and replaced the sim. Could just be a seating issue, couldn't it?