The UK’s PSTN switch-off is approaching, meaning the days of using the traditional network’s copper telephone lines will be over. Previously, 8x8 has published a history of PSTN and a guide to how PSTN works; but this time, we’re explaining how you can make sure your business isn’t caught out when the switch-off takes place.

Nine out of ten UK businesses still rely on the PSTN network to operate. Each of these organisations must switch from analogue systems and telephone lines to cloud-based and digital alternatives. As the December 2025 switch-off deadline approaches, there will be more pressure on service providers, field engineers, comms vendors, and everyone within the telecoms supply network to facilitate that change.

Last-minute switching may lead to downtime and delays

Due to the sheer effort required to migrate 20 million PSTN lines to digital, service bottlenecks are inevitable. For businesses who are delaying their transition, this means costly unplanned downtime is almost certain.

Downtime may have several causes, including:

  • Failing to engage with a digital communications provider and not having a transition plan
  • Not having a replacement for your legacy system when your PSTN contract ends
  • Bottlenecks to services throughout the supply chain
  • “Brownouts” that restrict internet bandwidth to 2mbps to force organisations to migrate

The true cost of downtime

Unplanned downtime is more than an inconvenience; it’s a significant drain on resources and a substantial cost. Across sectors, Forbes reports that the average cost of downtime is over $5,000 per minute. Even short breaks in operation pose a costly risk for companies.

Historically, downtime has cost larger organisations staggering sums of money in very short spans of time. In 2015, a 12-hour outage of Apple’s App store cost the company $25 million. Four years later, in 2019, Facebook lost $90 million due to an unplanned outage that lasted 14 hours—and saw its stock price fall by 2%.

And in 2023, an AWS downtime of several hours may have cost more than $150 million based on similar outages in 2017.

Compounding factors bump up the cost of being down

Unplanned downtime can cost a company money in many ways.

For example, productivity is lost if employees can’t provide services or factories can’t create goods. This obviously impacts revenue, and it means a portion of an organisation’s marketing budget is wasted, because the money spent to lead customers to a product is actually leading them nowhere. If businesses operate in heavily-regulated industries (or are required to have specific service level agreements), then downtime will bring in fines and charges too.

Worse than “run to fail” is failing to plan

In manufacturing, many companies use a costly and inefficient method of resource planning called “run to fail” or “run to failure”. This is where assets on a production line aren’t replaced until they fail.

Organisations cannot implement a run to fail method when it comes to their telecoms systems, however. They are critical assets that are necessary for the business to function properly. Without them, things won’t operate. These potential bottlenecks to services will exacerbate the issue by prolonging potential downtimes.

Organisations have to have a different strategy, and they must begin their transition planning now. Research shows that only 15% of SMEs have a formalised plan in place, and only 20% of large organisations do.

How to plan for the PSTN transition

Here’s a nine-step process to help your organisation start planning your PSTN transition (and avoid the costs of unplanned downtime):

  1. Look at your overall digital transformation strategy. Ultimately, changing systems should be viewed in the context of your overall communications and digital transformation strategy. How are your customers engaging? What trends are you seeing develop in the marketplace? These are all things you need to consider.
  2. Assess your legacy infrastructure: Identify and make an inventory of all your existing phone lines and equipment that are dependent on the PSTN/ISDN.
  3. Identify your communications requirements: With a catalogue of your legacy lines and equipment, you’ll be able to identify your requirements. Because the PSTN switch-off is an opportunity for digitalisation, you should also identify communications features that will help your organisation develop in the future.
  4. Engage a solutions provider: With an understanding of your resources and needs, engage a partner or provider to help find a solution that best fits for your situation. 8x8 has several options that can help, including cloud-based calling, virtual contact centres, or a single-platform enterprise-wide communications solution with voice, video, chat, and APIs for tech stack integration.
  5. Plan for number porting: Switching to a UCaaS solution allows you to port all of your company’s phone numbers. Determine which numbers you want to transfer and the timeline for this process. And be aware, each number can take up to 10 days to migrate.
  6. Infrastructure and security assessment: Ensure that your infrastructure is capable of supporting your communications environment. You may need additional bandwidth from your internet provider. Security is paramount, so you should ensure your processes will be compliant with data regulations and your systems will be safe.
  7. Migration testing and backup: Test the migration process to troubleshoot any obstacles or risks. Aim to set up a backup solution so you can maintain business continuity during the transition.
  8. Phase your new system rollout: You can make the change for your whole organisation in one go, or phase it. Phasing will help minimise disruption and maintain business continuity.
  9. Monitor and optimise your new system: Ensure your communications solution produces a wealth of data you can use to optimise your system and enhance its operations to drive efficiency and productivity. Capitalise on these tools, such as 8x8’s Conversation IQ, to increase your ROI.

To engage the help of 8x8 in planning your PSTN transition, get in touch with one of our experts who will guide you through the options and find the best solution for your organisation.

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