Not sure why the calls would be scam calls though. It would be one thing if they were legitimate marketing spam calls originating from phone number traceable back to the business originating the conversation but these are clearly cases where the number is faked in the new area code/country::city code in order to incentivize picking up. (Is that the car rental company? Is the hotel reaching out for some reason? Etc...)

I guess my paranoia here stems from this link in the OPs pdf[0].

0. https://venturebeat.com/2014/09/18/the-cell-tower-mystery-gr...