After decades of focusing on making and selling cars, Toyota is increasingly turning to partners to help develop expensive new vehicle technologies as it tries to transform itself into a mobility services company.

Under their new business alliance, Toyota and KDDI said they would jointly conduct research and development focused on telecommunication platforms that connect cars, homes, towns and users, among other projects.

To cement their ties, Toyota will buy 18.3 million treasury shares from KDDI, boosting its stake to 13.74% from 12.95%, on Jan. 29, they said in a statement.

As cars become more connected, the auto industry is facing competition from a growing number of global tech giants, including China's Tencent Holdings, Alphabet, Samsung Electronics.

This year, Toyota agreed with KDDI rival Nippon Telegraph and Telephone Corp (NTT) to work together on developing smart cities, with a 200 billion yen investment in each other.

(Reporting by Chang-Ran Kim; Editing by Tom Hogue and Gerry Doyle)