Many of my clients have a half dozen external modems on their systems, some for call-in, some for call-out and some for fax out. The two brands used are US Robotics and Multi Tech. I strongly prefer the Multi Tech, they're a lot smaller and they connect with everything - except sometimes US Robotics. One of my clients recently had to change his USR fax-out modem to Multi Tech because he was getting too many fax failures.