One question that always comes up is whether a single ISDN line is sufficient to support multiple users. After all, many individual telecommuters have a dedicated ISDN line. The answer is yes, with some minor caveats. An ISDN line will easily support half a dozen active users. Six active users typically means 50 people who use the Internet for email, Web browsing, and occasional file downloading. Most users notice better performance when they use an ISDN line instead of an analog modem connection with lower throughput, only when multiple users are simultaneously downloading large amounts of data, such as transferring files from an FTP site or viewing Web pages with many images.
Using Microsoft's Proxy Server with a high-speed modem or ISDN adapter is a low-cost, high-performance alternative to more expensive dedicated lines. ISDN has the advantage of providing faster connect times and faster throughput than analog modems. Proxy Server makes the connection transparent to network users so the network appears to have a dedicated connection to the Internet. A transient connection can further reduce expenses by letting you use a lower cost dynamic IP account. Most ISPs have dynamic IP accounts for analog modems in the range of $20 to $40 per month. ISDN accounts are $10 to $20 more expensive but still much less expensive than fixed IP accounts that typically run $250 or more per month.