Landline calls made from jail cost up to seven times more than the norm, a consumer group has said.
The cost of using landlines from prisons has led to a super-complaint being made to communications regulator Ofcom.
Evidence that half of all prison calls lasted less than three minutes due to their high expense led to the complaint being made by the National Consumer Council (NCC). The group also says that the calls can cost up to seven times as much as normal.
However, this pressure to cut costs - making a super-complaint now means that Ofcom is obliged to publish independent analysis on the charges for the service within 90 days - is to be resisted by BT and the government. The telecoms firm says that the extra security measures required by the calls explains the greater expense, while prisons minister Maria Eagle claim that an extra public subsidy would be needed if the change was made.
Philip Cullum, NCC acting chief executive, said: "We are extremely concerned by the nature of this market. Just because the consumers are prisoners it does not mean they should be exploited and pay well over the odds for telephone calls."
Ms Eagle responded by saying that she was "disappointed" by the NCC's complaint. "Prices are benchmarked against market conditions," she commented. "To reduce costs under the current contract would require a large subsidy at public expense."
