Song has not played for his national team since Cameroon's poor 2014 World Cup campaign in Brazil where he lashed out at Croatia's Mario Mandzukic off the ball during their Group A defeat in Manaus.
Song's inclusion in new coach Hugo Broos' first squad is a surprise after the 28-year-oldannounced his international retirement last year.
Broos has named two newcomers in the squad with Sochaux forward Karl Toko, 23, and Anatole Abang of the New York Red Bulls included.
Malaga goalkeeper Idriss Carlos Kameni was hoping to be fit for the match following knee surgery, but Broos has not taken a risk on him and has turned to Ajax's Andre Onana instead.
The qualifier against South Africa takes place on 26 March at the Limbe Omnisport Stadium.
Cameroon are currently top of Group M with maximum points from their first two games.
Goalkeepers: André Onana (Ajax); Guy Roland Ndy Assembe (Nancy;) Fabrice Ondoa (Tarragona)
Defenders: Allan Nyom (Watford); Nicolas Nkoulou (Marseille); Aurélien Chedjou (Galatasaray); Henri Bedimo (Lyon); Bitolo Ambroise Oyongo (Montreal Impact); Adolphe Teikeu (Sochaux); Sébastien Bassong (Norwich)
Midfielders: Jonathan Ngwen II (Unisport Bafang); Stéphane Mbia (Heibei, China); Alex Song (West Ham); Franck Kom (Etoile du Sahel); Landry N'Guemo (Akishar); Dany Ndi (Sporting Dijon); Sébastien Siani (KV Oostende); Tony Tchiani (Colombus Crew); Marvin Matip (Inglostadt)
Forwards: Vincent Aboubakar (Porto); Christian Bekamenga (Metz); Eric Maxime Choupo Moting (Schalke); Benjamin Moukandjo (Lorient); Jacques Zoua (GFC Ajaccio); Edgard Sali (St. Gallen); Anatole Abang (New York Red Bulls); Karl Toko (Sochaux)