If you end up spending more on your mobile this month, you can blame Ofcom, according to Vodafone and Orange.
Orange has already increased its minimum call charge for 'pay-as-you-go' tariffs from 20p to 25p and Vodafone is imposing an identical minimum charge - up from 21p - later this month.
Text charges on both networks will also rise from 10p to 12p.
The increases follow cuts made by Ofcom to the amount of money the companies are allowed to charge for cross-network calls, known as 'termination charges'. Ofcom reduced the rate from 4.18p to 2.66p earlier this year, and has plans to make further cuts.
A Vodafone spokesperson said, "This price rise comes after recent regulatory changes. During our discussions with Ofcom over mobile termination rates, we stressed that if the rates came down rapidly and dramatically, the cost of pay as you go was likely to rise as a consequence."