The senior civil servant in the Cabinet Office said it was "inappropriate" for vulnerable people to be hit with high bills for accessing vital public services. Cabinet Office permanent secretary Richard Heaton said his officials would work on guidance and principles for Whitehall to ensure people were not "ripped off".
Meanwhile, the Department for Work and Pensions announced it would offer a choice between 0845 and 0345 numbers to enable callers to choose the cheapest line.
The hearing followed a report by the National Audit Office, which said premium lines cost callers £56m, with nearly half the bill being run up while on hold.
Committee chairman Margaret Hodge said Cable and Wireless were making £1m from a deal with HM Revenue and Customs. Mr Heaton told her: "We will... help departments achieve a position which makes sense for, particularly, vulnerable consumers and make sure that they are not ripped off."