I think we need to remind ourselves of the bigger picture and why this change is happening. So we can then understand some aspects of the technical differences.
1) The current PSTN is becoming very costly, harder to fix and maintain. Moving to All IP and voice services moving to a VoIP/Internet based service will help reduce the cost, future proof maintainability & ease the integrations with modern systems.
2)Moving to All IP and VoIP/Internet based voice services is an enabler to the shift to full fibre and the withdrawal of
copper products. The government wants 85% by 2026 and 100% nationwide gigabit broadband by 2030. You will find over the next 8 years that areas where Fibre to the Cabinet is available will over built with Full fibre (FTTP) along with those areas that have no fibre today and when full fibre becomes available you will be encouraged to migrate onto it before potentially a full batch managed migration onto full fibre (FTTP)
There's already trial exchange areas that are currently in the process of withdrawing copper based products completely and as more areas get full fibre available to them there will be a push to move onto it.
3) Enabler to reduce the number of exchanges.
Here's some info graphics I've drawn to help explain (sorry it's a bit busy, trying to summarise it all in one picture)
Taking that into account. As you can see when the PSTN closes there will be no voltage transmitted down any remaining copper based lines in the network and as you move to full fibre (FTTP) you are now dealing with glass or plastic based cables which only carry light and no power output.
OFCOM's guidance after consultation on the move to All IP and VoIP/Internet based voice services states:
- "Principle 1 - Providers should have at least one solution that enables access to emergency organisations for a minimum of one hour in the event of a power outage in the premises"
- "Principle 2- The solution should be suitable for customers’ needs and should be offered free of charge to those who are at risk as they are dependent on their landline"
BT have applied with this guidance by offering a UPS device and working with those customers where there is no mobile coverage and those that are vulnerable to provide them with a way to call emergency services when there is no power.
However, that doesn't stop you from investing in a higher grade UPS or battery backup device that may provide more power output over a longer period. I would recommend in investing in an alternative way to store, generate and supply power anyway as more and more things are dependent on it.
Looking on Amazon there's a whole range of UPS devices with some that have a higher capacity and power output than others. Also it maybe worth looking at a device such as a Portable Power Station and Solar Generator if you are in an area where the mains grid maybe out for more than a few hours.
As for availability of mobile coverage, this too is constantly being expanded and upgraded along with the rollout of the Emergency Services Network (ESN) more and more masts are likely to have a backup power supply. If you are reliant on WiFi calling however, this will not work unless you have a backup power supply to continue powering your router and modem/ONT. Also remember that calling an emergency services number from a mobile will work no matter what mobile provider's network is available in the area as it will connect to any network it can find.
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