Telephony in the 21st century: from ISDN to VoIP

When KPN introduced ISDN in the early 1990s, the then ultramodern service was an important milestone in the history of the internet in the Netherlands. ISDN was one of the first major, important introductions of the former, just privatized, state-owned company. With ISDN, KPN - by many Dutch people then referred to as 'just' PTT - showed that it wanted to play a significant role in the internet's coming into existence in our country. In mid-2017, KPN announced that it would stop using ISDN on 1 September 2019. Within three decades, an initially state-of-the-art service has apparently become completely obsolete and superfluous. How did that happen? And important for ISDN users: which alternatives should ISDN forget?

"Go online"

Although ISDN is almost always mentioned in the same breath with the development of the internet, ISDN is strictly speaking a telephone service. This is mainly because there was not such a clear distinction between telephony and internet in the early days of the internet, from the late 1980s to the late 1990s. It was not until the turn of the century that the first private individuals in the Netherlands had access to a broadband connection (via ADSL). Until then, a 56k modem had to be dialed in (in most cases). The moment you dialed in with your modem was the moment that you very consciously 'went online'. It sounded like this:

Going online is in stark contrast to the way we use the internet today. In a world with 24/7 wifi, 4G (5G later) and in which babies and pets already have Facebook profiles, going online is no longer a conscious choice. That this choice had to be made so consciously in the 1990s was not only related to the costs (the 'telephone ticks') of your internet connection. To the annoyance of many parents and entrepreneurs, there was a second objection to being constantly online: your telephone line was busy.

Dialing in: busy tones and unreachability

Those who dialed in with their modem were no longer available by phone until the internet connection was interrupted again. This was because the modem was connected to the same connection as the landline. Internet and calling at the same time was not included.

Increasingly, consumers came across busy tones when trying to reach family, friends or businesses. It prompted KPN to introduce a new service: if you came across a busy signal, you could push the gate and hang up. You were now automatically called back when the line on the other side was free again, so that you did not constantly have to try it yourself. A nice service, but more symptom control than a real solution.

ISDN: always available

ISDN became available in the mid-1990s and promised a solution to these problems. By connecting an ISDN box to your telephone connection (often a Duovox or Quattrovox) you could transform that one telephone connection into two (Duovox) or even four (Quattrovox) different, digital connections. The ISDN box provided several lines with different telephone numbers. It allowed people with a home office to use four lines, for example, for the private telephone, the business telephone, the internet connection and the burglar alarm. Everything worked side by side and that guaranteed accessibility at all times.

ISDN also brought disadvantages, mainly in financial terms. ISDN boxes were expensive: hundreds of guilders for such a box, after which new DECT telephones often had to be purchased. A little entrepreneur soon lost a thousand euros in equipment when switching to ISDN. In addition, the subscription costs were added: four lines had to be paid instead of one, and costs could be incurred on all those lines at the same time. Those who called and used the internet at the same time also saw their bill rise twice as fast.

Yet many entrepreneurs in particular made the switch to ISDN, because it was the only way to be able to be online without sacrificing telephone accessibility. Private individuals also made the switch, although ISDN turned out to be a business product after the years went by. After the introduction of broadband, private individuals soon switched to an ADSL or cable connection and were able to free up their telephone line for telephony.

The 21st century: VoIP

However, they often did not return to an analogue telephone service (PSTN). With the introduction of ADSL (later VDSL and fiber optic) internet speed became important, and that speed became higher if the entire connection could also be used for internet. Fixed calling via the internet (Voice over IP, VoIP) was therefore introduced and immediately popular with consumers. Providers started offering total packages, including calling and using the internet (and later digital television) on one connection, via one modem.

The business market reacted reluctantly. VoIP was interrupted if the electricity supply was interrupted, it was unstable in the early years and therefore unreliable, and on most modems only one phone call could be made at a time. Many entrepreneurs have therefore, until today, kept ISDN for their telephony: that always works.

Then why does ISDN get up and running? The VoIP world has not stood still since the turn of the century - unlike ISDN. ISDN is just as pricey as ever: you need multiple telephone subscriptions and you pay user fees on each number. ISDN boxes are only becoming more expensive because demand is decreasing, and with that difference in reliability it is now also easy: VoIP achieved an uptime of 99.7% in 2017.

Switching to VoIP?

September 1, 2019 is the day and ISDN stops forever. The prepared entrepreneur would do well not to make a transition to VoIP until August, but well before that time. ICT for SMEs is crucial, and then you do not switch to a period when tens of thousands of colleagues (and competitors) do the same.

What should you pay attention to when you make the switch from ISDN to VoIP? First, always let yourself be good, personally inform about your situation. Every situation is unique, and although there is always a nice solution, this is a switch that you want to do well in one go. Let you continue don't frighten by possible investments that you have to make. You can continue to use almost all DECT telephones via VoIP and ISDN is almost never cheaper than a VoIP solution. Finally, when you switch, also look directly at nice extras that are available with VoIP, such as mobile calling via your fixed number or voicemail apps.

The VoIP world has not stood still. So be surprised.