In Finland several work sites reported errors of several centimeters between the height results when using different commercial virtual reference station networks and receiver brands. The real time kinematic results are calculated by manufacturer provided software containing in-house know-how. Further complications for calculations will arise when using physical or especially virtual base stations. In the study five commercial RTK-GNSS systems using a local base station and three virtual reference networks are tested for static accuracy at the Oulu Zone construction automation center at high precision static GNSS track. Errors on the several-centimeter level were found, and for one manufacturer, even larger gross errors were seen, possibly caused by operator error.