Mobile phone customers will be allowed to set their own limits on how much they spend, under measures set out by Ofcom. In a review of surprisingly high bills, the telecommunications regulator found that mobile customers were most likely to be affected: as many as 1.4m mobile phone contract customers may have suffered unexpectedly high bills in the past six months. The main causes of high bills include downloading data, primarily when the customer is travelling outside the EU, exceeding inclusive allowances or calling numbers not included in those allowances, or when a phone is lost or stolen and used by someone else. If a phone is stolen and thieves run up a huge bill, the consumer can be liable for the full amount, even if it runs into thousands of pounds. But Ofcom says it wants to \"explore the feasibility of limiting the amount consumers would be liable for if their phone was stolen\". It is urging providers to advertise more clearly the steps that consumers can take to protect themselves, such as locking their phone. The telecoms regulator has also called on mobile providers to help customers control the amount they spend, including the development of \"opt in\" measures, such as tariffs that allow customers to set their own financial caps and allow them to receive alerts about usage. It also plans further research to see if \"opt out\" measures would work better for consumers. If phone providers fail to do enough to help consumers, Ofcom \"may consider mandatory options to tackle the problem\". Marzena Lipman, digital policy manager at Consumer Focus said: \"Massive mobile bills when people return from trips abroad are the last thing they need. The next logical stage would be to also protect mobile phone customers in the UK. Consumers travelling in Europe are protected from unexpectedly high bills with a €50 (£42) cut-off limit, and consumers in the UK should be entitled to similar levels of protection. \"While some customers may want a higher data allowance, an opt-out default cut-off limit could help end bill-shocks in the UK.\" Ernest Doku, telecoms expert at uSwitch.com, welcomed the move to educate consumers more about the costs of using their phone: \"Consumers are still being stung with unexpected high charges and, whilst the onus is on the consumer to discuss options with their provider or switch to a package that more suits their usage, there is still an overriding responsibility on providers to look into measures to educate and combat the issue. \"A survey of mobile phone users carried out by uSwitch.com revealed that only a fifth of Brits check how much they\'ll be charged for using their phones abroad before they go, and four in ten have no idea of the costs.\"