Many thanks to SRAA contributor, Dan Greenall, who shares the following recording and notes:

Broadcaster: PTT voice mirrors from the 1970's Part 3

Frequency: various

Recption location: Ancaster, Ontario, Canada

Receiver and antenna: Hallicrafters S-52 using a longwire antenna

Mode: Single Side Band

Notes:
Point to point stations were commonly found on shortwave in the 1970's outside of the normal SWBC bands. They could often be heard transmitting a repeating test message so a receiving station could tune them in prior to conducting radiotelephone traffic.

1.  U.S. Army radio station ACA, Panama Canal Zone

2.  Oostende Radio, Belgium

3.  PTT, Dakar, Senegal

4.  Reugen Radio, German Democratic Republic

5.  Venezuelan Telephone Company, Caracas

6.  French Telecommunications Service, Djibouti

7.  British Post Office Phototelegraph Network (no location given)

8.  Canadian Overseas Telecommunications Corporation, 

      Yamachiche, Quebec

9.  ENTEL, Bogota, Colombia

10.  Belgian Telegraph and Telephone Administration, Brussels

11.  British Post Office, London, England

12.  France Cables and Radio Company, Fort Lamy, Chad

13.  PTT, Blantyre, Malawi

14.  East African External Telecommunications Company Limited,

        Nairobi, Kenya

15.  International Telecommunications Corporation, Abidjan, Ivory Coast

16.  Office Congolais des Postes et Telecommunications, Kinshasa,Democratic Republic of the Congo