The die marking certainly shows that TI provided the mask set... However, this has turned into a particularly interesting project because there is evidence that this device was fabricated by UMC, showing evidence of an increasing trend for IDMs to outsource certain products.
The Chipworks team used SEM analysis to look at the back end process used on the Nokia chip, concluding it could only have come from UMC's fabs. However, the transistors look more like TI's design. So TI either gave its transistor design to UMC for this project, or the front end was manufactured in a TI fab and the back end at UMC. The image below shows a TI tranny on the left and a UMC version on the right. Both designs use TI's differential offset spacer technology.