How mobile phone companies profit from handset loss

If your handset is stolen and thieves run up the bill you are liable for every penny. In no other area of life are consumers exposed in this way

It's time for mobile phone companies to pick up on unusual calling patterns early on.

When are mobile phone companies going to address the problem of handset theft and the absurd liability that customers face? Steve Jensen, who was chased for a debt of £7,000 for the last year by Vodafone, would certainly like to know, as would many of other victims of this issue featured in Guardian Money over the past few years.

Currently, when you take out a mobile phone contract, you sign up for all calls from the handset ... until you report it stolen. But if, unknown to you, a thief has got his hands on your phone and makes endless calls, you will also have to pick up the bill – however large.

Thieves, we understand, sell the phones on to backstreet call bureaus who then rent them out to users making international calls. That's why the bills can reach astonishing levels. You may have never called Pakistan, but that will cut no ice with the phone companies if hundreds of calls to Karachi appear on your account in a matter of days: you are liable until the phone is reported missing.

In no other area of life are consumers exposed in this way. If your credit card is stolen you have a maximum liability of £50.

Why have the banks developed sophisticated systems that detect unusual spending patterns? Because they have to pick up the bill. If the regulator, Ofcom, told the phone companies that an individual's liability is capped at, say, £100, they would soon institute bank-like controls. Vodafone declined to detail the systems it has in place to monitor airtime abuse and other phone companies have been similarly tight-lipped.

In Jensen's case it emerged that a text questioning whether he was making these calls was sent to his handset. Unsurprisingly, the thief failed to respond and the account remained open with the bill mounting up and up.

The phone companies have the technology to stamp out this problem but are oddly resistant to using it. It beggars belief that their systems cannot detect unusual calling patterns early on. Of course, consumers need to bear responsibility for looking after their phone – but a bill of £7,000? One can only conclude that the phone companies are profiting from crime.

• Guardian Money has highlighted the absurd cost of calling 118 directory inquiries, and the fact that so-called 0800 free-phone numbers are charged at 40p a minute from a mobile. After years of complaints from consumers, this week Ofcom finally announced it is prepared to tackle this issue. But don't hold your breath. It says it wants 0800 calls from mobiles to be free. It has also called for clearer charging structures to directory inquiries, and other chargeable numbers such as 0845.

A consultation has been announced, which is expected to conclude in the summer. As it is fairly straightforward, you would expect changes to come fairly soon. But this is the telecoms market and nothing happens quickly at Ofcom. We've been told not to expect concrete changes for 18 months. In the meantime, phone users will overpay millions of pounds for these services.