They gave the that whole "All your switches in the network have to be at the same software version or CorNet will not work" line when I bought the 150 system. Had they not "forgotten" to include that little tidbit in their quote that I had to present to the board to ask for the money I might have done that, but I wasn't going back and looking like an idiot so I told them to shove it - so they refused to set it up. I already had the cards, CSU, T1 purchased, etc, and all the documentation, so I sat down and taught myself how to program a Cornet Trunk... I had a bit of learning - the whole Master-Slave thing on CorNet, that you needed to use the newest CorNet protocol that was available on the 150 and be sure to use the same version on the 80EX end of it, and I had to figure out the COS translations between the two systems for permissions and stuff, but I fired it up and it worked just fine - with the only exception being that if you blind transferred a call without waiting for the other end to pick up it would drop the call about 20% of the time - that was it. I had maintained that since all the 150 had to do was communicate with my central 80EX for call routing, and the 80EX would actually transfer the call to the other sites, that the only system that really needed to be the latest software version, but they said it wasn't going to work... In the case of the HG1500 I did not own the card, and could not risk buying it and having it not work - grundies tend to get bunched up when it affects the wallet!!