In 2015, Nokia announced its plan to acquire Alcatel-Lucent, the French-American telecommunications-equipment company.
Nokia and Alcatel-Lucent announced the proposed all-share combination on April 15, 2015. The transaction was valued at approximately €15.6 billion on a fully diluted basis and offered 0.55 new Nokia shares for each Alcatel-Lucent share. The acquisition gained control of Alcatel-Lucent in January 2016 and reached full ownership later that year.
The deal strengthened Nokia in wireless networks, fixed-line infrastructure, routing, optical networking, and other carrier technologies. It also helped Nokia transform from a former mobile-phone leader into a company focused primarily on network equipment and communications technology.
The year in the question can cause confusion: 2015 was the announcement year, while the operational combination and acquisition process were completed in 2016. Nokia is nevertheless the single canonical answer. Alcatel-Lucent was not acquired by Huawei, Cisco, or Ericsson; Nokia retired the Alcatel-Lucent brand and integrated the business into Nokia Networks.