In 1979, the telephone system kept records of which line cards in a switch connected with other line cards in that switch or other switches. It was called SMDR (station message detail recording)and boiled down to essentially a record of circuit switching in the network .. this line card associated with the phone number XXX-XXXX connected with that line card with phone number xxx-xxxx. You couldn't know from that information the specific individual who placed the call, just that a call from that number happened at this specific time to this other number.
The metadata captured now from smart phones is much more involved, and given the nature of cellular and smart phones as personal devices tied to one individual, the data essentially shows your location at all times regardless of whether you are on a call or not, and all inbound and outbound communications whether voice or data are logged as well.
So the idea may be the same in principle but the type of data collected is much more personalized and involved.
In the Smith vs. Maryland case the phone company used the pen register on person’s line at the government’s “request.” No warrant was obtained, but the phone company at least knew that is was providing the information. Did Verizon know what the NSA was doing here? The Court ruled that there was no “search” so I guess no warrant was required.
An analysis of whether Smith applies in this case would need to compare the technology available in each case and the information derived.