BT, Virgin Media O2 and VodafoneThree lost a combined 972,000 mobile subscribers in 2025, their worst year on record. Low-cost rivals like Lebara, iD Mobile and Sky gained more than 1.5 million customers by comparison. The losses nearly doubled from 724,000 in 2024, marking a sharp structural shift in the UK telecoms market.

Household budget pressure is driving the trend. New entrants including Monzo, Lidl and Romanian operator Digi plan cut-price mobile offerings. Analyst Kester Mann at FDM CCS Insight said consumers are actively seeking affordable plans as the cost of living squeezes households. MVNO market share is expected to reach 26 per cent by 2030, up from 21 per cent.

The VodafoneThree merger's regulatory conditions locked in favourable wholesale rates for MVNOs, which Karen Egan at Enders Analysis called a collective strategic misstep. BT boss Allison Kirkby dismissed the threat, noting MVNO customers churn far more frequently than average subscribers. Major operators now compete for customers while simultaneously selling network access to the same rivals.