RESUME In 2003 a method for the solution of the integer phase ambiguity in InSAR data was proposed and demonstrated using laboratory data. The method uses the absolute phase and a rigorous radargrammetric model to derive the absolute 3-dimensional position of a target. This method appeared to show some capability for absolute, as opposed to relative, positioning and showed some benefits in applications where accurate DEMs are not available and there is little ground control. This paper explores this approach further, this time using ERS data for DEM generation, appropriate for remote areas. The methodology is applied rigorously and compared with alternative approaches using flattening and phase ratios. The results are quantitatively compared with GPS data and the benefits and drawbacks highlighted.