Hello Ian7210,
Welcome to Apple Support Communities!
We want to help you locate the number from a call you made.
If you were using FaceTime on your Mac, take these steps to view your call history:
"Return a call from FaceTime
The left side of the FaceTime window shows you all the calls you’ve made or received (unless you deleted your call history). It’s organized by date, with the most recent calls on top.
The Upcoming section appears when you create a link for a FaceTime call or when a link is available in Calendar, Reminders, Mail, or Messages. These links appear in the Upcoming section for a day or so; otherwise, they appear in the date-based section—for example, Last Week.
- In the FaceTime app
on your Mac, move the pointer over the call window, then click the Video button 
or the Audio button 
next to a call (or use the Touch Bar).
Tip: A Group FaceTime call remains active until all participants leave the call. To join or rejoin a group call that’s still in progress, click the Join Video button 
."
This Apple Support page has the full details: Return recent or missed FaceTime calls on Mac - Apple Support
Or if using your iPhone:
- "Open the Phone app, then tap Recents to view a list of recent calls"
Explains in detail here: View and delete the call history on your iPhone - Apple Support
The call would need to show here in order to view the call.
We hope this helps.
Cheers!
