Notes supplied by the Strahlheim Scholars guild:

The portals of Teldös were created to allow trade and further inter-species relations. The main cities of each race had a portal (possibly 8) with a few extra mixed in for good measure. To activate the portal, a collection of 4 gemstones must be placed in order on numbered plinths before the portal, then using a keystone focus the light of the sun or moon onto the diamond at the bottom of the portal to activate. It is believed that the portal connection causes the destination portal to display the 4 colors of the source portal (sort of a metaphysical caller-id).