The WIN 7 OS cannot see the modem. Here is a link to a microsoft forum. https://social.technet.microsoft.co...2f7a7532/windows-7-a-at-modem-error-633. I had this problem using a USB modem and had to get the latest driver, then go into Windows and mess with the COM ports. Yes it is a hassle but I finally got it. This is the model I currently use: https://www.wintecind.com/features/FileMate/Networking/hardmodem.html. Make sure you are only using COM ports 1-4.

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