I have 2 locations where EC 500 stopped working altogether. I downloaded Avaya's EC install and programming guide, and went through it, looking for any setting that might have changed. Everything in the manual is set as it should be in the Definity. I use 2420 phones. When I press the EC500 button, the screen states "EC500 enabled", but when you call it doesn't forward to the cell. Does anyone have any ideas?