Unlocking device


I have a pixel 4 on Verizon that I purchased in October. I have since paid off said Pixel 4. Verizon keeps telling me it's unlocked but whenever I insert an active T-Mobile or AT&T sim a notification pops up saying unsupported sim contact Verizon, I have always been current on the bill and I know mg phone is compatible with T-Mobile or Google Fi. Please help unlock my device that I've paid off