RDP International's predecessor, the Serviço de Ondas Curtas da Emissora Nacional, launched shortwave transmissions in 1936, which initially served the Portuguese cod fishing fleet in the waters of Newfoundland and Labrador, but by 1939 its remit was extended to provide information, music and Portuguese-language content to the entire Portuguese Empire.

RTP main shortwave broadcasting centre, known as "CEOC – Centro Emissor de Onda Curta" (lit.

SW transmitting centre) was located near Pegões, Portugal, has four 300 kW shortwave transmitters (1 TELEFUNKEN S 4005 and 3 THALES TSW 2300) and four 100 kW transmitters as backup, which served 6 transmitting antennas.

RDPi also used ProFunk GmbH centre in Sines, as part of an agreement made between the Portuguese State and Deutsche Welle; since January 2009, weekend broadcasts from Sines used Digital Radio Mondiale (DRM) targeting central Europe.

Nonetheless, some African radios relay some programmes from RDPi, specially Portuguese football games.