More than one in three Brummies face credit refusal because of their mobile phone, according to figures released by a credit reporting agency.
Checkmyfile.com analysed more than 1,000 credit files, taken at random, and found 37 per cent of people had mobile phone accounts with missed payments.
At worst these can lead to exclusion from the credit market or, at best, higher repayments because of hikedup interest rates.
Barry Stamp, joint managing director of www.checkmyfile.com, said he was shocked at just how many people had left themselves exposed to credit refusal in this way.
"Missed payments on mobile phone accounts are much more serious than most people realise," he noted.
"We find that many people are surprised to discover that their mobile phone account appears on their credit file at all. Many of our customers find they have an unblemished credit file, except for their mobile phone account, which lowers their credit score and reduces the choice of credit products available to them.
"Credit providers take a dim view of missed payments on applicant's credit files, as this can sometimes give an early warning of over-indebtedness. Most people have a missed payment on their credit files - we are all human - but a string of missed payments could easily lead to an application for credit being refused."
Some 34 per cent of English consumers had mobile phone account missed payments, compared with 36 per cent in Wales, and 39 per cent in Scotland.
Mr Stamp added that mobile phone companies themselves take a much more hardline approach to missed payments on competitor telecom accounts than other credit providers such as card companies.
"We see much evidence of mobile phone companies declining applications for a new phone apparently because of a single missed payment on a competitor phone account."