iPhone: calls and texts fail even with 4G data since Three-Vodafone merger — anyone else?

Hi everyone,

I’m wondering if anyone else has seen this.

My iPhone 16 Pro often won’t make or receive calls or texts — even though data works perfectly (WhatsApp, Maps, browsing, etc.). The signal icon shows 4G and there’s no sign of a problem until I try to make a call or send a text, someone tells me they couldn’t get through, or a text arrives hours late.

When it happens, I can usually fix it by turning off Wi-Fi and toggling airplane mode once or twice.

This has been happening only since the Three–Vodafone merger started rolling out. Do I need a new SIM, or is there a network-handover quirk affecting iPhones?

Would love to know if any other SMARTY users — especially those who’ve been through similar handovers — have seen this and found a lasting fix.

Thanks in advance!