Hi Pietro,
well, it depends what you would call a setup according to JAR-OPS procedures. Since (up to now) the only requirement for Dispatch Staff is to be adequatly trained, it depends on your CAA, whether or not they approve your dispatch center.
JAR 1.195 (b) does refer to the need for operational control
JAR 1.205 refers competence requirements for OPS staff
... there is also a reference for training requirements of ground staff, but I am quoting from the Internet JARs and my Net is slow tonight.
JAR 1.210 (a) demands procedures in place for ground ops
To cut it short, the name of the game with JARs is how you write your OM Part A and how your CAA is dealing with that matter.
As for FARs (especially for 121 operators) we are looking into a totally different setup. Due to the shared responsibilty between Dispatcher and Pilot, you have to have a adequate dispatch facility (which may be contracted out though). Please refer to FAR 121.107.
FAR 135 operators have it a little easier. Not too familiar with their setup, but FAR 135.77 details requirements for operational control. If I remember correct you do not have to have certified dispatchers, however, you need to know where your aircraft is (basic flight watch FAR 135.79, less restrictive than FAR 121, which requires you to be able to contact the flight while enroute).
If you require more detailed info drop me a line.
Are you considering to setup and airline in Europe or the U.S.?
Cheers. .fcit
P.S.: Ground OPS staff is usually a lot cheaper than pilots having to do their own arrangments. Also, you will have more duty time available for your crew, when you have dispatchers. This, of course, depends on the size of your operation.