ISDN in Plain English - 2 of 15
Before we look at ISDN in more detail, a quick summary of the benefits are; DDI - Direct Dialling Inwards gives the ability to have multiple telephone numbers even with a small number of lines, (or channels in ISDN speak). This allows for fax machines, PDQ machines, private lines, alarm systems etc, to be connected through the company telephone system making significant savings on line rental costs. See Fig1. It also facilitates the ability to answer the phone in different company names or department names. This is because these names will show on the LCD display of most modern phone systems, so the user only has to read the screen as they answer the call. It also gives the ability to analyse the response to different advertising and marketing initiatives, and dial direct to an individual's desk, by bypassing the switchboard and using a private/direct number.