What’s happening in 2025? We hear you ask.

Openreach, the network arm of BT PLC is switching off certain types of lines on the PSTN network.

This will mainly affect Traditional lines, ISND2e and ISDN30e. Broadband connections, where there is still an associated phone number and dial tone will require modification to a technology that Openreach have named SoGEA (Single order Generic Ethernet Access).

This is essentially pure broadband with no dial tone, allowing the 50 Volts equipment in the BT exchange to be decommissioned at the same time.




SoGEA has been around since 2020 so all new broadband orders that our customers have won’t need to be modified as we have forward planned the transitioning of technologies for some time now.

SoGEA is still FTTC technology, i.e. Fibre-to-the-Cabinet (from Exchange to Green Box) and a copper pair of wires from the Green Box to the customer. Where at all possible, it is advisable to have FULL FIBRE installed or FTTP/H as more commonly known.

ISND2e and 30e mainly serve Telephone Systems and there are two options when considering how to transition from these dial-tone technologies.

Option one is VoIP – Voice over IP or Hosted Technologies such as 3CX, Ring Central, 8×8 or the myriad of other Cloud based systems that require only a decent Internet connection.




The second option is SIP (Session Initiation Protocol) or Virtual Phone Lines.

By using special converters, known a Session Border Controllers (or SIP to ISDN converters), a company can, for a time, utilise the existing phone system and allow further time for planning and consideration of how long the system can be maintained.

If the system is say, under three years old, you may wait until the five-year mark or such time that spare parts are not available for the main controller to then look at alternatives.

The choice of Hosted Systems seems to be an ever-growing list.

It all comes down to features and functionality that you require as a business.

Recently, we have consulted a very small company with five users, that a simple platform with reasonably priced licences (a monthly licence is required for every IP handset connected via a broadband to the Hosted System provider) is all they would require.

To keep costs down, based on the fact that they mainly receive incoming calls, is NOT to have an inclusive calls package, which adds further coinage per user to the monthly rental.

Conversely, we have consulted a company with 120 users to opt for a system where they will only pay for the volume of concurrent calls, not the number of users connected to the system.

This method is more based on the ISDN2e / 30e and PBX method. I.E. a business may have had six channels of ISDN2e (six concurrent calls) and 20 extension phones on a phone system.

They would have bought, therefore only paying rental on 3 x ISDN2e (six channels). With the slight difference that on a VoIP system with concurrent call licencing, an internal call is also classed as a concurrent call – so you may need six SIP lines (equivalent of 3 x ISDN2e, with TEN licences for 20 users.

This method can save even more coinage in licencing terms.

So, call in Maximum Networks on how to transition your old ISDN2e/30e systems to SIP or VoIP!


Get in touch with the Maximum Networks team team today on 0330 102 7444 or using our contact form