The move, first reported by Spanish economic daily Expansion, marks a strategic shift for Telefonica which previously relied only on Huawei. The Chinese company provided Telefonica's 3G and 4G core networks in Spain.
U.S. President Donald Trump in May placed Huawei on the country's trade blacklist, citing national security concerns, and pressured its allies to shut out the company from their networks.
Huawei has repeatedly denied that its products pose a security threat.
Other European operators, including Britain's Vodafone and Deutsche Telekom, are also opting for multiple vendors. But Deutsche Telekom has called a halt to any new contracts until the debate on whether to bar Huawei on national security grounds yields some answers.
When the U.S. put Huawei on the blacklist, Telefonica had said it was reviewing the details and potential impact.
The core is the main hub of a mobile network. Telefonica has not decided yet who will provide the rest of its kit, such as its 5G antennas in Spain, the spokesman added.
(Reporting by Joan Faus, Isla Binnie and Gdansk Newsroom. Editing by Jane Merriman)