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The BT ISDN Switch Off: Everything Your Business Needs To Know

Telephone cord being cut by scissors in blue filter

Ready or not, here it comes…

In the fast-changing world of business communication technologies, some of the longest-serving are ISDN and the associated PSTN it runs through – and it’s not long before they are switched off. For those who are unsure about what’s happening and why (you’re certainly not alone!), we’ll start by explaining what these two abbreviations actually mean:

Public Switched Telephone Network (PSTN)

A PSTN is the original telecommunications network which allows users in different locations to talk directly to each other, over the phone. This has been used by businesses across the UK to operate telephone lines for many years.

In fact, they have been around since the 1800s and run on an extensive network of copper wires, spanning the country.

Integrated Services Digital Network (ISDN)

In comparison, an ISDN line is a more modern addition, created by BT in 1986. So even though a little more recent, ISDN technology is still over 36 years old! BT describe ISDN as:

“A high-performance service that delivers broadcast-quality voice and continuous, extremely reliable data transmission.” – BT

Given that an ISDN was the first solution to provide a continuous and stable connection, it has been the backbone in the growth of high-quality digital voice & video transmissions. ISDNs are also delivered through the original PSTN infrastructure, replacing old analogue landlines with digital ones. This allows improved functionality when compared to traditional telephones.

What is the BT ISDN Switch Off & why is it being shut down?

The ‘BT ISDN Switch Off’ refers to the termination of the ISDN network planned for 2025, which was first announced directly by BT in 2015. From this point all voice and video calls will be made over the internet, using Voice Over Internet Protocol or SIP Trunks.

We’ll come back to these to look at how they can help your business connectivity!

ISDN is being switched off primarily due to the scale with which digital communications have grown in the 21st Century. In 2019 for example, there were 80.9, million mobile handsets in the UK. This is more than one handset per person for everyone in the country!

As landline technologies have become increasingly digital, ISDN is unable to deal with this growth or provide the speed and proficiency users require, particularly compared to more modern technologies. In addition to this, it also has other restrictions, such as being tied to a physical office location for example.

SIP & VOIP Lines for business

As mentioned above, when ISDN is replaced there are two alternatives available for business – both of which run over the internet. We can take some time to explain these two options below:

What are SIP Trunks for business?

SIP stands for Session Initiation Protocol. This is an extremely flexible protocol within modern multimedia communications which allows real-time sessions between multiple participants or users. So don’t just think of traditional phone calls, other data such as video or instant messaging can also be transferred via a SIP connection. To sum up, SIP is the process which manages elements like the connection and termination of VOIP calls.

Benefits of SIP Trunks

What is VOIP for business? 

VOIP stands for Voice Over Internet Protocol and can also be known as IP Telephony or Internet Telephony. This is because the voice data associated with your call is packaged up by VOIP technology before these data packets are transmitted across your IP Network or the public internet.

Is VOIP or SIP best for my business?

As with most technology solutions, it depends on your exact business communication requirements! To sum this up at a top-level a VOIP system is usually the best option when you’re looking to fully overhaul your outdated phone system. This would include elements like new handsets and the associated software to manage your new system.

A SIP Packet is more relevant if you are looking for a solution which works with your existing phone system. You can then use one of the tried and tested solutions available on the market, such as 3CX or MS Teams Voice. Curveball Solutions is a designated 3CX Gold Partner meaning that we’re highly skilled in recommending custom 3CX systems.

How do I switch to VOIP or SIP?

In terms of making the switch, the complexity of this process depends on the approach you take. This can be extremely time-consuming in terms of liaising with the relevant parties if done directly, which is why it is recommended that you work with a specialist to help make the switch.

A professional communications provider such as Curveball Solutions takes the leg work out of this process as a fully managed service. There are just a few top-level questions you need to ask around your existing setup, such as does your internet connection allow VOIP and does your current phone system work with VOIP? The answer to both questions is usually yes if you’re using fairly modern products.

However, if for example your internet connection doesn’t have the level of bandwidth needed to accommodate additional calls, you will need to upgrade it. As a leading Managed Service Provider (MSP) we can recommend the right business internet connectivity for your needs. and supply your handsets or headsets if needed too.

Switching to a SIP or SIP Trunks is also a straightforward process given that they run over digital phone lines compared to traditional connections. This is great if you’re a growing business that might move office locations in the future. We can then help you in selecting the best phone system & hardware.

Don’t forget to port your phone numbers!

Most SME businesses have some form of location-specific or ‘landline’ number associated with them. This helps build credibility and trust with customers by demonstrating that you’re based in an office or physical location. Therefore, it’s safe to assume the vast majority of businesses will want to keep their phone numbers by porting them over as part of the ISDN switch-off.

This process can usually take a few weeks to implement, if not longer if your business has a large number of phone numbers that you’re looking to move across to your new phone system.

There can also be some back and forth with your current provider, so we’d encourage you to start this early. As part of our business communications managed services, we take care of all this for you so do ask your current company if they have this planned out too.

What are the benefits for my business in making the switch over?

From 2025 there will be no choice for businesses and all must switch over to VOIP or SIP options. Luckily though doing this provides a wide range of benefits for SMEs looking to improve their business communications. These include:

Reliability – Improved technology provides increased reliability across the board. However more modern solutions which run off IP Telephony also have improved disaster recovery functionality built-in, allowing you to restore backups direct without external support – much quicker if this is ever needed!

Speed & Functionality – This is one of the key benefits for your business. Not only are connection times quicker, but call management also becomes a breeze! This also includes wider multimedia formats and clever time-saving features such as direct CRM integration for example. Increased productivity allows you more time to focus on growing your business.

Cost Savings – Switching to VOIP or SIP Trunks can provide a multitude of cost savings. Not only can we provide your initial hardware in a cost-effective manner, you can also see ongoing savings with your associated line rentals, call charges and software licenses.

Improved Analytics – Modern VOIP solutions provide a much higher level of data analytics, meaning you can identify areas where your business processes can be improved. For example, if a lot of your resources are spent on customer service calls. other incoming calls could be missed. It may therefore be a good idea to add a Livechat function to your website or answers to frequently asked questions (FAQs).

How long does it take to switch from ISDN?

If you’re looking to get started on the process of switching your business over to a VOIP or SIP Trunk phone system, then it’s great you’re giving yourself time to plan this out.

There are some key questions you will need to consider to help shape this. We can help you collate the information needed if you’re not sure, through an informal and no-obligation chat with one of our cloud-hosted phone system experts. These questions could  include:

  • Is my current phone system IP compatible?
  • If so, should I consider a SIP Trunk option?
  • Is my business likely to move location in the future?
  • Does my business have location-specific phone numbers which need porting?
  • How many different phone numbers does my business have?

Once we have all the information we need, it can take up to 15 working days for a single-line transfer, or up to 25 working days for a multi-line transfer. To find out which is the best option for your business telecoms switch, get in touch for an informal chat with one of our experts here.


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