Nokia has posted better than expected quarterly profits, boosted by a one-off patent payment from China's Huawei.
But the company said its network business was set for another year of decline, despite promising North American sales.
The mobile industry, dominated by Huawei, Nokia and Sweden's Ericsson, is weathering the toughest part of a decade-long cycle as demand for 4G gear falls, while spending on new, mass-market 5G networks are unlikely before 2019 or 2020.
Nokia's fourth-quarter group earnings before interest and taxes increased 7% from a year ago to €1 billion, well above analysts' average forecast of €888m in a Reuters poll.
However, the profits were boosted by a one-off patent payment of €210m and operating profit from the networks business fell 25% year-on-year.
Nokia's chief executive Rajeev Suri said that while Nokia's network sales would remain weak this year, a potential rebound of spending by operators in North America could lessen the decline.
"For 2019 and 2020, we expect market conditions to improve markedly, driven by full-scale rollouts of 5G networks," Suri said in a statement.
He said investments in 5G would weigh on the networks unit's profitability this year, and forecast an operating margin of 6-9% for 2018 and 9-12% for 2020, compared to 8.3% in 2017.
Ericsson earlier this week reported its fifth quarter of losses in a row.
Nokia has coped with the downturn better than Ericsson thanks to its 2016 acquisition of Alcatel-Lucent, which broadened its portfolio and helped develop new products, including broadband equipment, fast traffic routers and high-capacity chipsets.