What is an ISDN line?

When we talk about modern communication systems, technologies such as VoIP, 5G or cloud computing usually come to the fore. But there are also solutions that, although they are years old, still play an important role in many companies. One of them is ISDN, or Integrated Services Digital Network. If you’re running a business and wondering if this technology still makes sense today, we’ll dispel your doubts!

ISDN – what exactly is it?

You remember the world before fiber-optic internet and super-fast Wi-Fi routers. That’s when ISDN was born – the digital telephone network that allowed not only calls, but also data transfer over a single line. It’s not impressive today, but decades ago it was a minor revolution. ISDN was a set of standards that had one goal: to convert analog landline telephony into digital. And it succeeded. ISDN technology enabled higher call quality and more reliable data transfer than earlier solutions.

Two faces of ISDN: BRA and PRA

In the ISDN world, we will mainly encounter two standards: BRA and PRA.

• ISDN BRA (Basic Rate Access) – offers two channels for data transmission (known as B channels) and one channel for signaling (D channel). Each of the B channels has a bandwidth of 64 Kbps. In practice? Simultaneous phone calls and faxing are not a problem.

• ISDN PRA (Primary Rate Access) – this is already in the league for the bigger players. Here we have as many as 30 B-channels plus one D-channel, making it possible to have multiple conversations in parallel. This is great for call centers or companies with multiple departments.

Why are companies still using ISDN networks?

Since we have modern VoIP exchanges today, why do we need ISDN? The answer is simple: stability and reliability. ISDN is sometimes indispensable where the quality of the connection must be perfect regardless of the circumstances. Fax machines, payment terminals, alarm systems – many of these devices still rely on ISDN. And where broadband Internet access is not available, ISDN is sometimes even the only sensible option.

ISDN in practice – how does it work in companies?

ISDN deployment requires appropriate terminal equipment, so-called TE and NT terminals, which communicate with the PBX. Most often these are routers with the appropriate cards. But don’t worry – you don’t have to be a network engineer to take advantage of this. That’s where we come in, offering a modern approach to the subject.

But how about something better than ISDN?

Although ISDN telephony was the backbone of corporate communications for years, the world has moved on. Today you have solutions that combine the advantages of ISDN, but are much more scalable and budget-friendly. An example? A virtual PBX from ITH. You don’t need a server room or a physical PBX – everything works in the cloud, and you manage it from a browser. You can easily plug in new numbers, set up forwarding, record calls or integrate the system with your CRM.

And if you already have your PBX? Great – use ITH’s SIP Trunk channel and make it a powerful tool that can handle dozens of calls simultaneously. Without jerking around with cables and expensive infrastructure.

ISDN – is it still the future?

The truth is that ISDN technology is slowly going off the scene. Many countries have already announced the extinction of this service, and operators are not accepting new applications. But that doesn’t mean you have to be left behind. On the contrary, it’s a good time to make a smooth transition to something better, without losing the functionality you’re used to.

ITH offers everything you need: from simple subscription solutions, to integration with CRM and ERP systems, to advanced systems for call centers. No term contracts, no hardware investments, easy expansion. So that your company’s telephony will finally start working on your terms.

Summary

ISDN is a technology that still has its place – especially where quality and reliability matter. But if you’re looking for something more flexible, better suited to today’s business realities, it’s worth looking around for newer solutions.

It’s not about throwing yourself at the news, it’s about managing your company’s communications wisely. And if you need someone to help you with all this who really knows – it’s worth having someone like ITH on your side. You want to talk about how to modernize your company’s telephony. We’ll introduce you to our network service offerings, explain how ISDN is structured, and present you with a package of additional services that can be useful to your business.

FAQ: the most common questions about ISDN.

What exactly is ISDN and is it still worth using?

ISDN (Integrated Services Digital Network) is a set of communication standards that allows voice, data, fax and signals to be transmitted over a single digital network. Although the technology is years old, it is still sometimes used in environments where reliable solutions are needed, such as call centers, hotels and credit card readers.

What is the difference between “B” and “D” channels?

Data-carrying channels (“B”) – allow voice and information transmission at up to 64 Kbps. Signaling channel (“D”) – is responsible for initiating calls, i.e. establishing and controlling conversations.

What opportunities does an ISDN deployment offer a company?

ISDN allows, among other things, direct dial extension (DDI), conference call handling and call hold without loss of quality, use of digital channels for fax, data or voice transmissions, and integration with telephone exchanges (PABX connection).

Does ISDN support DDI number ranges?

Yes. One of the significant advantages of ISDN is that it supports DDI number ranges, so you can assign different numbers to different departments or employees while maintaining a common main company line.

What is a multiple subscriber number and why is it used?

This is a feature that allows you to assign several numbers to a single network subscriber, such as different numbers for the office, fax and payment terminal. As a result, each of these numbers can be used independently, but operated by the same terminal device.