I am not able to receive calls from certain people in my contacts

Petey682 Said:

"I am not able to receive calls from certain people in my contacts: Some people say they call and the phone doesn’t ring"

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A Few Thoughts:

• Update your iPhone:

Go Here: Update your iPhone - Apple Support. See if you need to install an update - from the iPhone to a Third-Party app.

• Any Security Software Installed?:

Security Software could most retain have the option to block out callers, and filter out you from making calls.

• Something on the Callers End?

They (the callers) may have something on their end. Perhaps, they not dialing your phone number, but rather soon else's

Are those users blocked?

Block phone numbers, contacts, and emails on your iPhone, iPad, or iPod touch - Apple Support

See the section Manage your blocked phone numbers, contacts, and emails for how to un-block.