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Chapter 19. First You Need a Modem > Smart Shopping for a Fast Connection - Pg. 178

First You Need a Modem 178 Although ISDN might sound like the ideal solution for home and small business use, add up the costs before your decide. You can expect to pay about $150­$300 for the ISDN adapter and $100­ $200 for the phone company's installation fee ($250­$500 total). In addition, expect monthly charges from both the phone company and your Internet service provider (ISP). Phone companies typically charge about $30­$50 per month, and most ISPs charge $20­$30 per channel (for a total of $70­ $110 per month). Shop for the ISDN service before you shop for an ISDN modem or adapter, and ask your phone company for recommendations. The performance of your ISDN connection relies on how well your ISDN adapter works with your phone company's connection. Many phone companies have a pack- age deal that includes an ISDN. You also must choose the type of adapter you want: · External adapter--External ISDN adapters (sometimes called ISDN modems ) grab the digital signals from your phone company and stuff them through the serial port. If you have an older PC, the serial port might follow the 16550 UART (Universal Asynchronous Receiver-Transmitter) standard, which supports speeds only up to 115Kbps (10 percent slower than the top modem speed). To determine whether your COM port supports UART 16650 or later, choose Start, Settings, Control Panel, and click or double-click the Modems icon. Click the Diagnostics tab, click the COM port you want to check, and click More Info. You might need to install a high- speed COM port or, better yet, install an ISDN adapter card instead. · Adapter card--An ISDN adapter card plugs into your PC's expansion slot, so it does not have the potential bottleneck you might experience with an ISDN modem. · Router--A router enables you to connect several PCs to a single ISDN line. If you have a me- dium-size network, a router provides the perfect solution for multiple connections to an ISDN line. With smaller networks there are other solutions, including external adapters that have two or more serial ports.