ISDN was long regarded as the standard for high quality corporate telephony. However, many providers have already been converting their technology to All-IP for years, and the ISDN shutdown is now almost complete. This means that the majority of users are already making calls via Voice over IP (VoIP).

Convince yourself of our inexpensive and powerful VoIP connections for private and business customers.

Why is ISDN switched off at all?

The ISDN infrastructure is simply outdated and far too expensive.

With Voice over IP (VoIP), consumers use their telephony via the Internet connection. This means that telephony providers no longer have to operate two separate networks, which means that VoIP providers can offer their connections much more cheaply. While ISDN uses complex and maintenance-intensive technology in every exchange, there are only a few central servers for VoIP. The ISDN system is therefore outdated.

So-called SIP trunks, which are registered directly in the classic or virtual IP telephone system, can be used to bundle numerous call channels. SIP trunks can be dialed through, i.e. number blocks can be used. They are also easier to manage than traditional corporate trunks.

In addition, companies that have switched to All-IP can use a central telephone system in a computer centre (hosted PBX). This means that complex technology no longer has to be operated at every location. Thanks to the SIP trunks, the processes are centralized, which makes maintenance much easier. All-IP is not only cheaper, it is also more flexible than ISDN and therefore future-proof.

But don't worry, the switch to All-IP is no problem. Even if it is easier for private customers than for companies, you don't have to worry about losing your business telephony.

The important thing is to switch over in good time! Therefore, it is important to know which requirements you place on your business telephony.

More information about the conversion to ALL-IP

Why you can manage your business telephony via easybell SIP Trunks

The largest German ISDN network operator is Deutsche Telekom. The switch-off of ISDN and the conversion to the new technology are also largely completed here, although the goal of having all customers switched over by the end of 2018 has not been achieved. easybell has been offering Voice over IP for more than 10 years. With SIP Trunks, we have also been offering high-performance services for business customers for 5 years. Our many years of experience and numerous satisfied business customers allow us to take a relaxed approach to your switch from ISDN to All-IP.

easybell offers flexible SIP Trunks at favourable conditions. The principle is very simple: Instead of an ISDN connection, you can use your Internet connection to make phone calls. The SIP trunks are stored in an IP telephone system at your location or in the cloud. This allows you to either use your existing telephone numbers or set up new ones. In contrast to ISDN, a SIP Trunk can not only be used at one location but anywhere in the world. The only requirement: you need a broadband connection. This saves costs when opening up additional locations and makes you and your company flexible and independent. Employees can also be reached, for example, in their home office or on business trips at their office number.

If you want to switch from your ISDN connection to SIP Trunks, we recommend that you do so:

Business easy - your tariff for the All-IP changeover

For only 4,19€/month* you get 10 lines, i.e. you can use up to 10 parallel calls for up to 30 extensions. This is an extreme cost advantage compared to the conventional ISDN offer.

The 3 most important points that speak for Business easy

Secure telephony from Germany

  • encrypted telephony
  • automatic fallback solutions
  • servers are located in Germany
  • our easybell fraud protection guarantee

Unbeatably fair conditions

  • no minimum contract term, can be cancelled monthly
  • crystal clear telephony in HD quality
  • optional hardware offerings such as the Snom IP Phone D785

Optional minute packages as Fair Flats

  •  one minute packet for all extensions.
  •  up to 71 percent savings
  •  find out more here

3 questions we often receive before switching from ISDN to SIP trunking

For most companies, switching to All-IP is uncharted territory. In the following we have once answered the three most frequently asked questions to easybell on this topic:


Can I take my business numbers and number blocks with me to easybell?
That is no problem. Simply port your previous numbers and number blocks to easybell free of charge. We will be happy to do this for you. Find out more here.

However, you can optionally purchase number blocks - of course without a monthly surcharge.


What equipment does my company need to switch to All-IP?
If you are currently using an ISDN telephone system, you have two options: Media Gateways as digital voice converters for analogue systems or VoIP extension modules for ISDN systems (manufacturer-specific). In the long term, it is advisable to switch to analogue or virtual IP telephone systems.

A further proposal is therefore to inform oneself about a telephone system in the cloud. In addition to the maintenance and repair costs, you can also simply save space here. Find out more here.

What bandwidth do I need to use the SIP Trunks?
You need a bandwidth of 80 Kbit/s per voice channel for external calls. Any Internet connection that supports this speed can become your corporate connection - anywhere in the world! If you make internal calls via the local telephone system, the broadband connection is not used.

Any questions left? No problem!

Do you have any questions? Do not hesitate and ask us! The excellent easybell customer service has been awarded with numerous tests and is happy to help you with words and deeds!


*plus legal VAT.


Author: Julia Jünger
Last edited on: 18. May 2021