We just upgraded our Definity G3R to a S8700 over the weekend. Now all of our modems (configured as modems)will not dial out to external systems - ie other Avaya PBXs, etc. The modem line disconnects carrier. We have tried changing the stations to faxes, 2500 etc. and this still does not work. We are using ISDN lines for outbound dialing. I have tried changing the COR, COS etc. nothing seems to work. We have echo cancellation turned off on the trunks. Any suggestions?