I was just doing some time back Voice related services for Call center - i have information as below this may help you, quite old (not active on voice side now myself - other than just help my collegues)
every side of the coin has Pros and Cons, we need to look what business want and choose more of Pros side.
http://josonone.blogspot.com/2012/05/uccx-resource-groups-or-skills.html