Not receiving certain txt SMS messages, iPhone, ID Mobile

[slope]

For the last 10 days approx. am not receiving passcode txts from my credit card provider nor some other sites who require them = major pain. Asked 3 friends to txt me and all fine there + can send txts to them. Last week received 3 week old voicemail notification txts at the same time, which were related to voicemails on 3 different days past.

Have checked all the usual iPhone settings - which must be ok anyway as personal txts come through? Same issue using Wi-Fi Calling as well as mobile coverage when I'm able to get to a place where there's a signal.

iPhone 13 Pro (up to date with latest OS), ID Mobile SIM (uses Three network).

Any ideas what's occurrin'

[rusky]

I had loads of issues with three and SMS to the point that I moved network. They kept blaming the phone and even tried to get me to factory reset it despite me trying the SIM in a gsm modem with the same result!
Not that it helps you now but I feel you won't get this resolved with three.

[slope]

Mmmm, the ridiculous of life where there's no apparent sense to IT?

9 old too late to be of much use, txts arrived this afternoon, in a batch. The originating txts were sent at different times over a span of 3 days.

Turned off the iPhone 13, removed the SIM card, with difficulty - it requires more force with the straightened paper clip than seems sensible. Bunged SIM back in and turned phone on again.

Used the iMac to log on to the credit card website, which then required a txt generated passcode. This was using Wi-Fi Calling and Airplane mode to save battery usage, as no mobile reception at home. BOOF! Almost instant receipt of txt again restored?

No idea where the decidely worrying and problematic heebie jeebies were occurring, or why