Hi SLF,. .. .Yes, WAAS, EGNOS and MSAS are all interoperable. A receiver that works with one will work with the others (thats the plan anyway <img border="0" title="" alt="[Wink]" src="wink.gif" /> ). All of these systems (and the new Indian version called GAGAN) are all Satellite Based Augmentation Systems (SBAS) to use the generic ICAO term. . .. .At the moment EGNOS is not operational, but the EGNOS Test Bed is, its known as ESTB and is a cut down version of the full system to allow trials to take place. Some of the current WAAS handhelds will work with ESTB, others won't. Thats because ESTB broadcasts a 'don't use' message to prevent users utilising what could potentially be misleading guidance but some (non aviation) receivers ignore this message.. .. .Here is the URL for the ESTB website:. .. . <a href="http://www.esa.int/export/esaEG/estb.html" target="_blank">ESTB Web Page</a> . .. .Hope this helps <img border="0" title="" alt="[Smile]" src="smile.gif" />