The short answer is no. Some will tell you that yes this is possible and that it will save you a great deal of money as their system can adapt. That is unfortunately blatantly false. To begin aside from and wireless access points all of your existing network cabling is in the walls and not in the ceiling. The second and most important reason is that the power requirements needed from your PoE switch are very specific and anything but an 802.3bt capable PoE switch with the appropriate PoE budget will not work.
