Systems supplier Unisys has refused to pay a $6m (£3.9m) telephone bill for a year because of a dispute over a lack of call information.
The dispute has been used by the Telecommunications Managers' Association as an example of the types of billing problems companies face when trying to analyse bills supplied by telcos.
David Walker, Unisys' European telecoms manager, revealed the unpaid bill at the launch of TMA's free Billing for Business Analyzer.
Walker said: "We can't pay a bill for $6m, and haven't been able to for over a year, because we can't quantify it. The telco accepts there is a problem, but so far they haven't been able to supply the information we need."
Walker said Unisys spent around $100m a year on telecoms worldwide, running its own voice and data network controlled by a string of regional network managers. Around $8m is spent in the UK and $20m across Europe.
Walker would not name the supplier at fault, but confirmed the telco was still being used by Unisys. He was hopeful of a settlement soon, but said the problem illustrated why 3-5% of his budget went on managing expenditure.
The TMA launched its Billing for Business initiative 18 months ago, and originally planned to have the analyser in place last spring. Technical problems and ongoing discussions with suppliers wanting to supply information delayed the project.
Now, most suppliers are supplying data, which sees users keying in their requirements for the charging and presentation of their bills, and the analyser providing them with the most suitable range of suppliers.
TMA director general David Harrington said the service was badly needed. "We estimate the cost of bad billing to UK business is worth around £1bn a year."
The free service, for both TMA and non-TMA members, offers straightforward access without a password. Users who want two-way communication with suppliers must first register, but the service is still free.