WATMIKE Said:
"Making calls: Hi. I bought a used iPhone recently. I can't make or receive calls unless they are WhatsApp. Even they fail when incoming. I didn't realise for a week or so but the silence became apparent I had missed several calls."
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Calls With WhatsApp:
A. Contact WhatsApp:
Contact them, asking them for some input.
B. Delete WhatsApp:
Save what need be, and then delete what's app. See fi this then goes away.
C. Return this iPhone:
Where was this purchased? You may have a damaged phone. This is the site the seller should have used, prior to selling it to you; the seller should have known better: What to do Before you Sell, Give Away or Trade in your iPhone or iPad – Apple Support
Troubleshooting iPhone Calls:
A. Go Here: If you can't Make or Receive Calls on your iPhone - Apple Support
B. "No Service":
"No Service" is shown on the top-left corner of your screen. So, go here to fix that: If you See No Service or Searching on your iPhone or iPad - Apple Support
C. Whom to Contact:
Contact your Carrier, as they are the one who provide you with the service of Cellular.