Paying your mobile bill late or not at all puts your chances of obtaining credit, including mortgages, at risk.
One in seven people has paid a mobile phone bill late or not paid it at all, according to a survey by Ocean Finance revealed.
Missed or non-payment is particularly a problem for young adults, with nearly a quarter of 18- to 24-year-olds affected – compared with 14% overall.
Half of those who took part in the poll blamed delays on unexpected large bills - with call charges or overseas roaming charges cited by 12% as reasons why they couldn't pay their mobile phone bills.
Some 25% admitted that unexpected excess data usage had meant they delayed or didn't pay their mobile phone bills.
A further 35% claimed other monthly bills had caused them to run short of money, which suggests that some people are not prioritising their phone bills.
Mobile phone contracts are a form of unsecured credit and missing even one late payment in the last year can affect your chances of having a loan or credit card approved.
Mobile phone companies are stricter than other lenders when declaring that a customer has defaulted on a payment, doing so after just three missed payments. This compares unfavourably with credit card companies that allow six missed payments before declaring a customer in default.
Ian Williams of Ocean Finance says: "Many people don't realise a mobile phone contract is unsecured credit and that they could be jeopardising their credit records by not paying.
"A common situation is that people take their phone on holiday abroad, rack up a large bill and then either can't or won't pay."
He added: "When you are applying for credit, including mortgages, lenders will look at any late or missed payments from within the last three years, but the impact of any defaulted payments lasts for six years. So a default on a mobile phone bill from five years ago could still be stopping you from getting a loan, new credit card or, in a worst case scenario, a mortgage, regardless of how good your credit record is otherwise."