Dialling from Custom POI's on 2820

[beemerboy9]

I have a 2820 to which that I have sucessfully loaded custom POI's.
What format (or formatting sysmbols) does the custom POI require in order for the Dial Phone number option to appear in the Advanced options menu?
Is any particular POI editing software required to support this functionality? - I am using POI edit V4.5.1.