The company 's roots can be traced back to then '' ' Loreto F. de Hemedes , Inc. ' '' , owned by Robert " Uncle Bob " Stewart , an American war correspondent . The company started with the launching of its first AM radio station in Manila through Radio Broadcasting Station , DZBB . It went on air on March 1 , 1950 using the frequency of 580 kHz of the AM band , broadcasting from the Calvo Building in Escolta , Manila . Its early radio coverage highlights were the crash of President Ramon Magsaysay 's plane in Mount Manunggal ; the eruption of Mount Hibok-Hibok and various local elections in the Philippines . DZBB became the first radio station in the Philippines to use telephones for live interviews
crash
1957 Cebu Douglas C-47 crash
GMA Network (company)