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The Zoom 56Kx achieved admirable 45.3-kbps throughput when making V.90 calls over clean phone lines. With compression enabled, text-file transfers sped to 90 kbps. But just as we began to suspect performance would be neck-and-neck with the internal from start to finish, we noted a startling difference. While the internal had no trouble with any of the noise or distortion we injected into our lines, the 56Kx began to falter. In simulated long distance situations, the external often dropped below 35 kbps. With many nationwide ISPs setting up local numbers that auto-forward calls to central sites located in other states, this could be troublesome. But despite the speed reductions, we could still depend on the 56Kx to connect and deliver files without fail.
Over modem-to-modem V.34 connections, the Zoom external moved data at a reasonable 30.4 kbps. Although it still performed a bit behind the internal Dualmode for impairments handling, excessive noise didn't affect its V.34 throughput capabilities nearly as much as it did with V.90 calls.
Where V.90 isn't yet available, the 56Kx will automatically switch over to negotiate a K56flex connection. In addition, Zoom makes firmware updates available for free download from its Web site, allowing you to keep your modem current using its flash ROM. A detailed Quick Start guide is included to get you fully functioning in no time. You also get fax software from Communicate Lite, plus the usual assortment of free-trial CD-ROMs for various online services.
While the external Zoom Fax/Modem's design reminded us of a kitchen appliance, it does have a few nice touches, such as the 12 LEDs on its front panel. In addition to common functions such as carrier detect, transmit, and receive, the modem has specific lights to indicate whether it's connected at V.34 or 56k rates.
Zoom has built a reputation for excellent 56K modem products. While the 56Kx Dualmode lacks some of the tenacity of its internal sibling, it's not exceptional.