We are trying to use the Telephony web service to replicate softphone telecommute mode capability, specifically to place a call between an originating number defined by the user (e.g. their cell phone) and the destination.

The problem is that it appears that the originating number must be a physical device (phone). I've tried doing this in combination with ec500, but in this case the call goes out to the destination number but NOT to the ec500 associated cell phone.

Is there a better way to achieve this requirement??

On your Communication Manager get a SAT session and run the command 'list trace station xxxxx', where xxxxx is the station where EC500 is enabled. See if CM is attempting to dial the cell phone when a call arrives. Does it work when you make a call to an EC500 phone without using Telephone Web Service? I wouln't think the web service would have anything to do with this feature not working, as Communication Manager is the one that controls the setup and the call to the cell phone.