I have a 20 port AD-40 voicemail system that is connected to a NEC 2400 PBX.The integration is done through digital ports so the only thing the COM port is used for is to control lights. I am having problems with getting the message waiting lights to turn on and off. I have isolated the problem to the COM ports on the voicemail system...port one is used for the dial up modem (works fine). COM port 2 is used for lamp control(is bad) How do I swap the COM ports so that I can get my light control back? I don't really need the modem to work