Can't place calls to flip phones on iPhone 13 Pro
Why can’t I call someone one who has a flip phone
[Re-Titled by Moderator]
iPhone 13 Pro, iOS 16
Why can’t I call someone one who has a flip phone
[Re-Titled by Moderator]
iPhone 13 Pro, iOS 16
Check your iPhone settings
Go to Settings and turn on Airplane Mode, wait five seconds, then turn it off. Check Do Not Disturb. Go to Settings > Focus > Do Not Disturb and make sure it's turned off. Check for any blocked phone numbers.
If you can't make or receive calls on your iPhone - Apple Support

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Can't place calls to flip phones on iPhone 13 Pro