I just got an Apple USB modem in order to send and receive an occasional fax on my Macbook. I tried it at home where we have a simple phone setup through Telekom and the setup and execution were simple and flawless, as is usually the case with Apple stuff. At my shop, I have an ISDN connection through Arcor. The cable that goes from the wall into the phone is a different plug than fits into the Apple modem's, which looks like the typical RJ 11 size. When I bought the modem on eBay, the seller included an adapter which fits into the modem receptacle and goes to the left-hand receptacle in the phone junction on the wall. In order to insert it, I have to remove the phone cable from the middle receptacle. (Let me say right here that I clearly don't know what the different receptacles in the wall junction are for, except that the middle one is the one for the phone.) I tried to send a test fax and there was no dial tone. I would appreciate it if someone would give me a little guidance so that I can send a fax over ISDN with my Macbook and of course receive as well.