You need to get back to basics. I would find it hard to believe but years ago a UCS used to put Y cables on Hitachis and I know of one company that used to put certain cables on the H3 that Y'd and they were set up for modems and they had resistors across one side on two and three to stop data from bleeding when a modem was plugged in. Get rid of the darn Y cable and plug the cable from the digiport directly into the system port of the H3 then try it. depending on the cable you get you may or may not need the null modem connector.

Those IP to serial port converters can be VERY Particular. How savvy are you on networking/slash IP protocol? If the cable fix above doesn't do the trick and you aren't too familiar with IP protocol you really might want to hire some help 'cause you could be in over your head and I guarantee you you will be way over the head of the PMS person if you start asking questions. That being said I have worked with one or two good PMS people but they are usually few and far between and from what this yahoo has been telling you he isn't one of them. While you would absolutely need the dataset for the PBX interface (which 55 footer explained earlier in the post) but for Call accounting -ABSITIVELY not.