John,
What version of software is running on your system? If it is high enough there is a built-in PSTN Calls report you can do through the System Administration and Diagnostics.
The easiest way to find out is to go to the SAaD tool and after connecting press the down arrow to open up the tabs view. Look to the far right tabs and you should see Reports as one of the tabs. I think you can figure the rest out from there, but if not then just post again and someone will help you further.
Thanks,
TE
