Tech support asking for SIM Card ID or ICCID on iPhone6 (SIM card not supported)

I keep getting "activation required" and then "SIM Card not supported" or something like that, and there's no way to get past that screen. My service is Straight Talk. My phone then only works when I pop out the SIM card (and connected to WiFi). But of course texting and calling do not work. Tech support then asks for my SIM card number or ICCID. They are adamant that I should find this under Settings / General / About, but it is not there. Finally after 5 minutes of back and forth, she instructs me to look on the back of the SIM card itself, and there it is!

I kept emphasizing to her that my SIM card is _not inserted_, because that's the only way I can even get to Settings, but without the SIM card inserted, it's not going to show you the ICCID. If you run into this situation with a tech support person, get out a magnifying glass and look at the back of the physical SIM card.

As far as why I keep getting "activation required", I still have no answer as to why this keeps happening. People keep telling me to just get a new phone, but this one still works fine otherwise.