top of page
Voice Services | SIP | VOIP | ISDN | Red5 Networks Ltd | ISP Norwich Norfolk

Voice Services

It's not just big corporations that need high-quality telephone services. More and more people are working in small offices or at home.

Red5 Networks Voice Services

Despite the fact that IP services are now widely available, there are still 32 million+ telephone lines, live in the UK, and it's still the primary, telecommunication service in use by businesses. Our extensive range of services ensures we have something to suit your business needs.

Managing the process of ordering and installation can be a nightmare, but we keep you informed every step of the way. From ordering, installation, billing and ongoing support, our experienced team of technical staff and dedicated account managers ensure everything runs smoothly.

With many years of experience in the market, we specialise in providing lines and calls to customers across the UK, with clear and competitive pricing. 

But does my business need physical telephone lines?

These services continue to underpin ADSL and FTTC services, so are essential for many business connectivity needs.

However, in 2025, BT will conduct major changes to its services, permanently switching off important communications networks.


Red5 Networks can advise you on precisely what is going on, why it is happening and what you can do to stop it causing problems for your business.

Red5 Networks Voice Alternatives


Our hosted voice system will scale from home workers, very small single offices to multi-site networks and large corporate headquarters.


Our ISDN over UltraNet service allows you to take advantage of the substantial savings available from internet telephony (VoIP) without the need to replace your existing phone system.


Future proof your business and move to SIP Trunks. Replace your ISDN and keep your Telephone System.

Are you ready for the ISDN & PSTN switch off?

BT announced in 2015, they are switching off the PSTN and ISDN in 2025. This is the biggest change in the telecoms industry for over 30 years, but what does this mean for you? Below we will answer many of your questions on your business' connectivity future. 

2025 can still seem a long time away for the big switch off. In potentially very little time, businesses could be left urgently needing to make changes they hadn’t planned and budgeted for in regards to their communications. So please get in touch now!

There’s a lot of uncertainty around what the switch off will mean to business users, why the change is happening and what needs to be done beforehand. Below we have put together a selection of common questions to help explain what is happening. If you’re still uncertain, please get in touch and a member of our team can help get you prepared!


What is the PSTN and ISDN Switch Off?

The Public Switch Telephone Network (PSTN) is aging and will reach the end of life in December 2025. The PSTN supports a number of Openreach products which include, line rental and Integrated Services Digital Network (ISDN). At the end of December 2025 traditional telephony, including fixed lines and services in the Public Switch Telephone Network (PSTN) will be switched off and withdrawn from service.

Why is PSTN and ISDN being withdrawn in 2025?

The PST Network allows calls to be made over copper telephone lines and fibre telephone lines using analogue signaling. As broadband services have increased in reliability and quality over the past 10 years, the PSTN has evolved to support this change to an almost completely digital network. So there will no longer be a need for most, traditional fixed line analogue services in the coming years. Traditional fixed lines and calls will cease to exist. Maintaining the legacy infrastructure and equipment serving the PSTN is now ageing and becoming more difficult and costly to maintain.

What other services are impacted by the 2025 closure?

The PSTN currently supports many products but most providers fail to mention the connectivity products which are using these services like ADSL Broadband and Fibre To The Cabinet (FTTC) Broadband which will be impacted in 2025. This is because the physical line product is being withdrawn, therefore there is no underlying telephone service to support the broadband. There will be alternative ‘broadband only’ services available where the latest fibre services are not yet in place. 

What happens if my business has ISDN?

Even though you have a few more years to purchase ISDN lines, it doesn't change the fact that it is old technology and will soon be obsolete. We at Red5 Networks strongly advise that if your telephony contract is up for renewal that you start exploring alternatives, now. If your contract is still live for a few more years, just ensure you have enough ISDN phone lines to cope with your growth plans before you can no longer purchase any more in 2023.

Can Red5 Networks provide the PSTN replacement services?

Moving forward, Red5 Networks' replacement service will be a Single Order (SO) variant of ADSL or Fibre broadband services. When these Single Order (SO) broadband products are provided there will be no voice on the telephone line and no dial tone, this means Red5 Networks will need to provide some form of VOIP service like a Hosted service or Session Initiation Protocol (SIP Trunking) service to provide the voice telephony element which would replace the traditional telephone service.

Is it simple to migrate across to Hosted VoIP or SIP?

With Red5 Networks, it couldn't be simpler. We manage the whole migration, keeping you in the loop at all times. We can retain your current telephone numbers, including any DDIs and the whole migration can take as little as 3 weeks. Red5 Networks are in a unique position to offer our ISDN over Ultranet service which can have you migrated even sooner. Please check out our Ultranet page for more information.

What happens to alarm and payment lines services after 2025?

During the Public Switch Telephone Network closure of all these services, they need to be tested with the new IP technology and the SO products. Red5 Networks can discuss your individual requirements with you and any other special equipment can be tested by the equipment manufacturers.

Are there benefits of migrating away from PSTN services now?

Cost Savings

With the introduction of reduced line rentals and free calls to the most popular destinations called by businesses, annual telephony budgets can be cut and used in more beneficial areas to support customers and employees.

Simpler Installation

IP services can run over most internet services and can be available within hours of ordering the service, meaning no more lengthy waits for BT Openreach engineers to physically connect you to the exchange.


IP technology allows you to take your numbers anywhere in the world with an Internet connection, meaning they are no longer tied to the Openreach exchange area they are held. Also, you are able to keep your old phone number.

Better Resilience

For safeguarding purposes, businesses cannot afford to be ‘off the grid’ when there is an Internet or hardware outage. IP technology can failover to backup connections or be diverted to another destination to ensure the business is always contactable even in an outage.

Fraud Protection

Businesses are prone to being targeted by fraud during holiday periods. Although IP technology is much more secure and difficult for fraudsters to successful tamper with, it can also be configured to automatically block outbound calls when a daily call spend is reached.

Future proof your business and move to IP Technology

Replace your ISDN and keep your Telephone System

What is SIP Trunking?


Session Initiation Protocol (SIP) Trunking is a way of providing telephone lines using data rather than fixed lines. It gives you the ability to make outgoing and incoming calls using IP technology without needing to completely replace your current telephone system.


SIP is the ideal replacement for fixed lines and offers greater flexibility and resilience whilst being at a lower price point.


What do you need to move to SIP?


SIP uses VoIP technology to make and receive calls so you will firstly need some form of connectivity. We recommend high speed fibre or if you need more than 20 concurrent calls we recommend a dedicated connection like Ethernet.


You do not need to move your telephone system to a hosted system as SIP provides you with the ability to use your existing service. However, you need to make sure your telephone system is IP Compatible.


Why choose us for SIP?


We understand that moving to IP can sometimes be a big step for a business so we’ve taken the time to ensure our staff can help you move your numbers to a new IP network as seamlessly as possible. We also offer some great features and benefits, just take a look at some of them below.


Our SIP Benefits


Savings – Moving to SIP can save you up to 50% on line rental compared to ISDN channels


Inclusive Calls – We offer inclusive call packages to local, national and headline UK mobile networks (EE, O2, Vodafone and Three)


Compatibility – Our SIP Trunks are compatible with all the major telephone system venders so we can support you.


Fraud Protection – Our Trunks come with call spend management, alerting and enhanced fraud detection protecting your business.

Explore related services

Hosted Cloud Voice Services | SIP | VOIP | Red5 Networks Ltd | ISP Norwich Norfolk
Ultranet Wireless Network | Red5 Networks Ltd | ISP Norwich Norfolk
Hosted Cloud Voice Services | SIP | VOIP | Red5 Networks Ltd | ISP Norwich Norfolk
City Skyline

For more information on our services give us a call on 01603 859669 or send us an enquiry

bottom of page