Not a contact, can’t answer

If you keep Silence Unknown Callers on, make sure Dial Assist is enabled in the same Phone settings menu. This helps identify incoming calls with non-contact numbers.

Can you explain the phrase "can’t answer"? Here is an explanation that you may check at your end...

There are many reasons why you might not be able to answer calls. Here are some of the most common possibilities:

1. The phone is on silent or Do Not Disturb mode: This is a common reason for missing calls. Most phones have a silent mode or Do Not Disturb mode that can be turned on accidentally. You may have enabled Calls from (See the pic below)
   1. 
2. Phone is out of range: If you are in an area with poor cell service, you may not be able to receive calls.
3. User is busy: You might be in a meeting, driving, or otherwise occupied and unable to answer the phone.
4. User is ignoring the call or text: It's also possible that you are unknowingly ignoring the call, perhaps because you don't recognize the number or don't want to talk to the person calling.

By considering these possibilities, you can get a better idea of why you may not be able to answer your calls.

Being unable to reply to texts is only possible if you are blocked or you are in an area with poor cell service, you may not be able to send texts.

How iMessages and SMSs work is explained below

iMessage (Blue) -

• iPhone to iPhone: requires internet (Either over WiFi or Cellular Service) as it is sent over internet protocol. Needs Activation on your device.
• iPhone to Android: Not available

SMS/MMS (Green) -

• iPhone to Android: does not require any internet it is sent over cellular voice protocol. Needs to be enabled by your Carrier for the SIM used by you.
• iPhone to iPhone: When iMessage is not activated or the device is not connected to the internet either over cellular or WiFi
• You need to have an SMS/MMS plan enabled by your carrier for the SIM/eSIM that you use on your device. Apple Inc does not provide SMS/MMS services.

It will turn from Blue to Green if you have enabled "Send as SMS" and whenever your iPhone is not connected to the internet it is sent as SMS (green) to all iPhone users.