For example, we know messages are saved in
~/Library/Messages/chat.db however where are calls saved? Is there a folder or file?
I found my history at:
if you want to be able to decode the destination phone/facetime numbers stored in
storedata, there are currently two solutions available:
Both allow to decrypt the addressee number, but the latter is available as executable files for different platforms.
You can view a list of recent calls in the Phone app, just tap "Recents" at the bottom.
I would imagine that this list is saved in an iTunes backup of your device. There are a number of apps for Mac and Windows that allow you to explore the backup file and extract quite a number of the files. I do not know if the list of recent calls is saved.
On occasion I have used iExplore for viewing the contents of the backup. There are others out there that do similar things.