Nokia has always been an electronics manufacturer, but about a decade ago they realized that their mobile phone division was losing a lot of ground to Apple and Android. They partnered up with Microsoft to create the phones for Microsoft's mobile OS and then sold off the division to Microsoft a few years later. Part of that deal was that Microsoft got to use the Nokia brand made famous by their pre-smartphone devices that were incredibly rugged and reliable while still affordable.

When this happened, you had two different companies using the same company name. Nokia Networks was the main brand and still made lots of equipment like routers, switches, cell tower radios, and optical networking equipment. Nokia Mobile/Nokia Phones was essentially a different company, though as I understand it after Microsoft left the cell phone market Nokia bought the company back but spun it off as its own company also using the Nokia brand.