The companies also questioned the necessity of the measures, arguing that the impact of short-term power outages would be minimal and could be largely mitigated by nearby locations.
They also called on regulators to focus on improving grid resilience.
Mobile phone companies currently offer battery backup at their locations, but the extent of coverage and duration of backup power vary considerably across networks.
The rules proposed by Ofcom include a requirement for a one-hour battery backup at all mobile sites and a four-hour backup in broadband cabinets.
The call for greater resilience stems from concerns that Britain’s vital communications networks could become increasingly vulnerable to crises.
Ofcom cited extreme weather events such as storms and floods in the winter of 2021/2022, which left some communities without any means of communication, including calls to emergency services.
This trend has been exacerbated by the switch from copper to digital landline connections, which are more susceptible to disruption in the event of power outages.
BT has delayed the launch of the new technology following several serious incidents in which so-called “telecare” devices – personal alarms designed to be activated in the event of a medical emergency or fall – failed due to digital landlines.
An Ofcom spokesperson said: “We have not put forward any proposals at this stage. The costs we have set out in our call for proposals are for illustrative purposes only.
“We are reviewing the responses we have received and will work with industry and government to identify and pursue options to resolve any issues.”
