The Recordings Tapes are collections of Telco recordings for vacant codes, busy circuits, disconnected numbers, etc. There are included some tandem "InWATS test" recordings. These tapes have no call progress, just one recording after another.  

A list of the recording ID numbers, thanks to Mark of Louisiana, is in Recordings-codes-circa-1980.pdf.  

Since this is a 1980 document, not all information will match the "Recordings tapes" which were made in 1971-1974.  
Note that in this document Canada in a separate list at the end.

  Now we have the 1975 recording ID list as well, thanks to Phil Lapsley. This will be more accurate to identify the recording IDs on my "recordings" tapes.