We have a CRM application which is developed in Clarion apparently. We want phone numbers to be clickable so that our phones will dial the number. The developer for the app seems amiable to the idea of this, so long as he can make it work
with skype, MSN messenger (or whatever the current app is). He has sort of asked me what method we would use but I am simply unsure how to answer him so I am posting this oddly vague question in the hope someone has some idea what I 
am trying to ask even though I am not certain myself. 

I suggested he make phone numbers (Some of which are edit boxes in the application, and some of which are read only display boxes (as they can't be changed), hyperlinks, with something like this: 

<a href="tel:+1800229933">Call us free!</a> but he was asking about standard windows outputs or something which confused me. 

I think the common thing is tapi, but I am not sure if TAPI can make use of Skype or other selected apps which intercept that particular call.

Sorry this is so vague.