Chosen Solution

I factory reset the phone, I’ve changed my APN (by going to my service provider and letting it send it to my phone itself), I have gone into safe mode with no luck, and there is no Wi-Fi calling on this phone. sometimes when I’m at work and there’s no service it says I have no SIM card. then usually restart the phone and it comes back. when I make a call it says airplane mode is on but it’s not at all. and when I shut down my phone sometimes it’ll say airplane mode is on. I turn off airplane mode it’ll show the outline of the bars for signal but there are no bars in there. and yes I have service I checked my data plan on the website. I don’t have this phone ZTE Blade Z Max. I have the ZTE Citrine

There may be a warranty on the phone. If so, you can send it in to ZTE and get it repaired.

You might have to get a new SIM Card.

Did you buy it from a carrier? They might’ve rooted the phone to prevent other carriers from working. (This happened to me)can u still text?heres a link to ZTE’S user manuals https://www.zteusa.com/support_page