The Phone App on iPhone comes with “Announce Calls’ feature, which can be used to make iPhone Speak the “Name” or “Phone Number” of the Caller, whenever an incoming call is received on your device.
As you must have guessed it, this feature makes use of Apple’s popular digital assistant “Siri” to compare the incoming phone number with your Contacts List and Speak or Read-out the Name of the Caller as it appears in the Contacts List.
Since, Siri gets the name of the Callers from your Contacts List, it won’t be able to announce the Names or Phone Numbers of Callers that are not listed on the Contacts List. In such cases, Siri announces that you have received a Call from an Unknown Caller.
Make iPhone Speak Caller Name
All that is required to make iPhone speak or announce the Name or Phone Number of the Caller is to enable the ‘Announce Calls’ feature on your iPhone.
When this feature is enabled, the usual ringtone on iPhone will still play, but Siri will take over from there and Call out the Name of the person that is trying to call your device.
1. Make iPhone Announce Incoming Calls
You can follow the steps below to make iPhone speak or announce the Name or Phone Number of anyone that is trying to call your device.
1. Go to Settings > Apps > Phone > tap on Announce Calls option.

2. On Announce Calls screen, you can select when you want iPhone to announce the Name of the Caller.

Always: Your iPhone will always announce the Caller Name or Number, regardless of whether you have headphones plugged in or not.
Headphone & Car: Your iPhone will announce Calls only when you have headphones plugged in or if you are inside your car.
Headphones Only: Your iPhone will announce Calls only when you have the headphones plugged in.
Stop iPhone Announcing Caller Name or Number
If you no longer want iPhone to announce the Caller Name or Number, you can stop iPhone from announcing the Caller Name or Phone Number by using the following steps.
1. Go to Settings > Apps > Phone > select Announce Calls option.

2. On the next screen, select the Never option to stop iPhone from announcing the Name or Phone Number of the Caller.

After this, you should no longer find Siri announcing the name of the Caller, whenever an incoming call is received on your device.