Hi Karl,

If you want to make an audio call using FaceTime on your Mac, take a look at the follow information from the Mac OS X User Guide in the section entitled Use Your Mac to make and receive phone calls:

Make and receive FaceTime calls

You can make FaceTime video and audio calls to anyone who has a Mac or an iOS device that supports FaceTime. All participants must be connected to the Internet. FaceTime video and audio calls use data, not cellular minutes.

You can also make and receive phone calls using FaceTime on your Mac. These calls use cellular minutes. For more information, see Use your Mac to make and receive phone calls.

Open FaceTime for me

Make a video or audio call

1. If you’re not signed in to FaceTime, sign in.

2. In the field at the top of the FaceTime window, enter the recipient’s email address or phone number.

    

   You can also enter the name of anyone in Contacts, or click the Contacts button to see all of your contacts.

    

   For information about adding contacts, see Contacts Help.

3. To start a call, click the Video button or the Audio button .

    

   If you click the Audio button and you’re set up to make phone calls, you can choose whether to make a FaceTime audio call or a phone call.

4. If a video call is declined or unanswered, click Message to send an iMessage to the recipient, or click Cancel to cancel the call.

    

   To send an iMessage, you and your friend must be signed in to iMessage.

Cheers,

Hi Karl,

Thank you for using the Apple Support Community. Due to the nature of your issue or question you may find more information by using another one of Apple's support resources - https://getsupport.apple.com/GetproductgroupList.action

Take care,