First of all I've installed the 3cx PBX on Windows XP embedded on a small fanless ITX barebone. See: http://www.tragant.de/produkte/inde...ukte/artikelDetail.php?id=1050&setLanguage=EN This creates a really nice, small silent embedded PBX. Works perfect. Nice Box, nice PBX software. I'm very enthusiastic. Perfect alternative for Asterisk based solutions, they are pretty complex to configure and with a descent GUI, they need (how weird for a Linux application) a much bigger footprint. I've had some installation problems, If anyone is interested, ask me. Problem I have is with the registration. With my BT-100 it first does not register. Later on it suddenly does, but I could not make calls. I discovered that if I turn off STUN on the BT-100, it works like a charm. Then I wanted 3CX connected to my Lancom VOIP gateway (1823 VOIP). First trying to register 3CX on the Lancom (using lancom as a line/trunk on 3CX). Same kind of problem. 3CX did not register, when I emptied the STUN fields registration went ok. Then trying to connect my Lancom analog port to 3CX as an extension; not working. Problem is, I cannot disable STUN on the Lancom. But that shouldn't be necessary. There probably is a strange STUN conflict between 3CX, probably my router and the client. If usefull, I can make an etherreal capture to check out the SIP messages. In the 3CX logs I cannot see anything strange. B.t.w. the problem is also there if I install 3CX on a normal XP machine. I hope you can help me.