"14 This position was reiterated in Ofcom’s 2017 Connected Nations Report which stated that “Emergency services access should be provided in accordance with the General Conditions” and “Technical solutions for ensuring reliable operation of new voice services, for example during localised or widespread power outages, should provide levels of protections equivalent to that provided by traditional means"
REf: Guidance: Protecting access to emergency organisations when there is a power cut at the customer’s p...
My interpretation of the above is that, in order to facilitate emergency calls by VOIP customers, Ofcom recommend that telecoms providers should either ensure that their customers have a mobile phone to hand even, if it means them supplying one free of charge, or supply a free UPS the recommended capacity of which would be 1 hour (see elsewhere in this document)
