Millions of mobile phone users are facing data rationing and price hikes after Rachel Reeves left telecoms firms to suffer the rising costs of energy.
The Chancellor left the telecoms sector out of a tax-relief scheme, leaving firms facing the full force of energy price rises caused by the war in Iran.
The multi-billion-pound British Industrial Competitiveness Scheme (BICS) acts as a taxpayer-funded lifeline to give relief to 10,000 businesses with a 25 per cent discount on their electricity bills.
Now some of Britain's biggest networks have warned they may be forced to slow down speeds and hike costs for consumers.
However, telecoms giants including VodafoneThree, Virgin Media O2 and EE have been left out of the scheme despite consuming under one terawatt-hour of electricity each year, enough to power 370,000 homes.
As a result, the firms are drawing up emergency contingency plans to manage their own bills.
Among the measures being considered are slowing speeds, restricting access during periods of high demand and charging customers a premium for usage at peak times.
Most rationing will be targeted at voice calls and mobile data usage.
Customers could face online downtime, slower speeds or even charges under plans being drawn up by telecoms firms
Operators may also consider offshoring call centres to offset the cost of energy bills, just as jobs were beginning to return to the UK.
The cost pressures could also lead to 5G rollout plans being shelved in another blow to British jobs.
One network warned that 9,000 jobs could be made at risk if investment plans are slowed down by rising costs.
The BICS scheme will cut costs by up to £40 per megawatt-hour from 2027 by exempting businesses from certain extra charges that currently support green energy and back-up power supply systems.
An additional one-off payment in 2027 will be given to an extra 3,000 businesses, including companies in the automotive, aerospace, steel and pharmaceuticals sectors.
The Chancellor previously said the plan will help UK businesses compete and create jobs despite the uncertain economic backdrop.
Industry insiders warned that mobile networks are officially classed as critical infrastructure and should be included in the scheme.
The price of electricity has risen by 33 per cent since the war began and could continue to rise.
A spokesperson for VodafoneThree told The Sun: 'We are disappointed that the Government has chosen not to include the telecoms sector in the British Industrial Competitiveness Scheme.
'We urge the Government to consider the impact of rising energy prices on the vital telecoms sector that unlocks growth in all parts of the economy.'
A Virgin Media O2 spokesperson added: 'If the Government wants growth, productivity and resilience, it cannot overlook the digital networks the country depends on.'