ISDN Connectivity by Jeff Newman and David Willis Planning for ISDN The most important thing to do when considering ISDN is to find out exactly what your network needs are and determine if it is right for the task. A projection of your future needs could also save you a lot of money as your network grows. After it has been determined that all locations that you want to connect are ISDN-capable and support your required bandwidth (56 Kbps or 64 Kbps) and you have decided exactly what you want to do with the connections, check out the latest issues involving that topology and the latest standards developments [see www.microsoft.com/windows/getisdn/orderwm.htm for an excellent tool for this]. Then establish a cost model. Consider the following: Service fees fro m local telco for each location (installation + monthly + per minute) Long distance charges, if applicable Cost of equipment (NT1 + TA, NT1 + bridges, NT1 + routers, etc.) Cost of ISP services, if applicable Determine your maximum number of connected minutes per month to create a budget, for example, $25 a month + 2 cents per minute per channel. Therefore, you pay $2.40 per hour for two B connections. If you want to be connected three hours per day, 20 days per month, you will need $144 + $25 = $169 for a month of service, just for the local telco portion of your ISDN connection. Long distance fees and ISP charges would naturally needed to be factored into this as well. Once you have determined your projected costs, you may realize that you have passed a threshold to where you may wish to go with a dedicated service, either a negotiating unlimited ISDN service or getting a 56-Kbps leased line. Also remember that telephone companies are notorious for wanting to raise tariffs, especially with new technology that they are finding expensive to implement and when they run across groups who take advantage of this technology in ways that the telephone company didn't intend. Telephone companies are, however, regulated by state public service commissions and must convince these organizations that the tariff adjustments are warranted before they can be enacted. May 16, 1996 Print This Page E-mail this URL