Do not take into account what Blue Lava has said to you. VoiceMaster is a very expensive solution for this.
First, you can connect all the Quintums into a border element. Thus, they will share routing information and will distribute the load between themselves.
Secondly, you can use the Quintum external gatekeeper / call routing server. It also costs money, but is much cheaper than VoiceMaster.
Thirdly, you can use an external gatekeeper/softswitch. GnuGk (the most popular one) is not able to do port capacity tracking and load balancing so far. However Acua gatekeeper is able to do that. It runs on Linux / FreeBSD and is free of charge.