Pulling the plug – are your phone lines about to get switched off?

Will I be affected? 

Probably - unless you already have been! There are a lot of acronyms in the telephone world, which can make it difficult to understand exactly what is being switched off: 

Analogue telephone lines 

• The most common example of this is the landline phone in your house. If you still plug a phone into a wall socket in your house, you have an analogue phone line 

• Fax machines – not nearly as common as they once were, but still relied on by some businesses 

• Alarm lines – alarms in business premises are often connected directly to a monitoring centre, and historically, this would likely have been done using a dedicated analogue phone line 

• Lift alarms – the emergency buttons in lifts often use analogue phone lines 

• The phones in your business – if you can’t dial from one phone to another just using an extension number, there is a chance that you are using an analogue phone line for each handset. 

ISDN telephone lines 

Although often billed as the ‘analogue switch off’, it is actually everything connected to the UK PSTN service that will be going – and this includes ISDN lines. 

• ISDN lines were often used for business phone systems. If your phone system can handle multiple incoming calls to the same number at the same time, or if you own a range of consecutive phone numbers used by different staff, you might be using an ISDN line 

• If you see any of the following acronyms on a phone bill or in documentation, it’s likely to be ISDN: 

• ISDN30e 

• ISDN2 

• ISDN 

• E1 

• PRI 

• BRI 

• PSTN 

If you only see either of these instead: 

• SIP 

• VOIP 

then you’re already using the replacement technology – congratulations! 

What do I need to do? 

The first challenge is figuring out if you still have analogue lines – only once you’ve worked out if and where they are can you decide what to do with them. Here are some broad recommendations below to start you off. 

Alarm lines 

Alarm lines (fire, security, lifts) – get in touch with the company that services your alarm or lift and ask them about switching to a GSM (mobile phone type) connection, with battery backup. They may also suggest a network connection so the device can call out across your internet connection, but unless all your network equipment is UPS backed (for the kind of duration that someone might be stuck in a lift during a power-cut…) then GSM/battery just for the alarm is the way to go. Remember that someone will need to test connection and the battery regularly! 

Fax lines 

Do you really still need physical fax? There are several e-Fax type services out there that will receive a fax on your behalf and send it on to you as an email, and vice-versa.  

If you absolutely must have a real fax machine in the corner, then you might need to get a specialist involved – not all of the VOIP/SIP providers can cope with fax connections. 

Business phones 

Pre-pandemic, phone was king but nowadays you’ll find yourself using Teams, Zoom, Webex or other video calls and meetings more often. This is a good opportunity to ‘right size’ your phone connection; there is no point replacing an old 30 channel ISDN line with a 30 channel SIP trunk if your business only actually needs capacity for five simultaneous calls now. 

In an ideal world, you would just buy a ‘SIP trunk’ (a virtual phone line that uses an internet connection to transmit calls) and connect that to your phone system. However, if you’re currently still using ISDN and have a phones-on-desks type system, it may not support a SIP connection (at least, not without some extra licencing). 

One choice would be to replace everything with a more modern system at the same time as going SIP. Now might be a good opportunity to move away from handsets and on to a computer based system so your phone travels with you. This is often (but not always) a ‘cloud’ system. 

The other choice is to find a way to get the old system talking SIP, whether it likes it or not. For this, I would always recommend using a Session Border Controller (SBC) of some kind, even if your system can talk SIP directly. You can think of the SBC as a kind of ‘firewall for phones’, and will often handle network firewalls, NAT rules and the like much better than the phone system can by itself. This could be a physical device, usually about the size of a network switch, or a virtual machine if you have virtual infrastructure. 

A physical SBC also gives you the option of converting between SIP and ISDN. Originally designed to allow people to connect their old phone lines to a virtual phone controller by converting the incoming ISDN line to SIP for the ‘last meter’, they can be set up in reverse to convert an incoming SIP trunk back to ISDN so that the old phone system never needs to know anything has changed. 

If you can, get in touch with whoever looks after your current phone system to discuss the options. Don’t get pressured into a shiny cloud based system because ‘it’s the only choice’ – whilst not a bad idea, there certainly are alternatives! 

Get in touch

Who ya gonna’ call? (And more importantly, how?) Waterstons! Find out more about how comms within your business could be optimised by getting in touch with rich.hall@Waterstons.com