So what's happening, and what can you do about it?
The biggest hike comes from Vodafone, which is raising its minimum call charge on some contracts from 15p to 25p - a rise of 66%. That's a huge amount of money to pay in order to be put straight through to voicemail. Meanwhile, pay-as-you-go users will see the cost of a text increase from 10p to 12p, and calls will increase from 21p a minute to 15p a minute. The changes will come in from 14 July.
At the same time, from this Friday, Orange is increasing its minimum call charge for pay-as-you-go customers from 20p to 25p.
All mobile phone companies are reacting to the fact that moves from Ofgem have stopped them ripping people off in a number of ways - such as termination rates - so they just have to find new ways to squeeze more from customers.
At best all this toing and froing will leave costumers no better off despite the regulator's actions. At worst, if you have the wrong type of contract you'll be considerably worse off.
In the short term, the answer may be to reconsider your network. However, in reality, there's a good chance you will still be tied into a long contract. The other fly in the ointment is that between them, these two companies run about half the mobile phones in the UK. There are concerns that these moves will mean there's nothing to be lost for other providers to follow in their footsteps.
The answer is therefore to ensure you are on the best contract for you. Dig out your bills and make sure that you are not going over your allocated number of monthly calls and texts on a regular basis. If you are busting your limit, give your mobile company a call and negotiate. They should be willing to offer you a deal for more minutes for far less than you are already paying.
If you are on a pay-as-you-go tariff it may also be time to move to a contract. As a rough rule of thumb, if you regularly spend £20 a month topping up, a contract will be a more cost-effective option.
But what do you think? Are your mobile bills going up? Do you feel that the regulator is doing anything to protect you? Let us know in the comments.