I’ve just had some more info from Ofcom on the implementation of national roaming in the UK.
National roaming for mobile 999/112 was available in the UK in the early days of GSM but was switched off at the request of the emergency authorities because of the volume of hoax calls. Therefore there is a wariness around switching it on again without safeguards.
There is no overall authority in the UK with responsibility for delivering emergency services so the planning process has to involve all the separate stakeholders, for example the Ambulance Service and the Police Service come under separate government departments. This means that Ofcom can’t simply order it to happen but has to work towards a consensus approach.
However the good news is that Ofcom hopes that national roaming will be available within the next nine months.