O2 isn't a fan of BT and 3's joint campaign to drop inter-operator mobile charges, Terminate the Rate. The two companies recently petitioned telecoms regulator Ofcom to scrap these charges completely, saying it would allow operators to offer better value, cheaper call packages.
O2, however, begs to differ, saying that if Ofcom does scrap these charges, operators will be lose money and be forced to raise prices on services or implement use-by dates on prepay credit. The UK's largest mobile operator believes the move would hurt low-usage and prepay customers the most, and even lead to people reducing mobile usage.
However, BT recently hit, saying in a letter to The Guardian that 'we have been there before." The company cited an example in 2002, when Ofcom first proposed lower inter-operator mobile charges, or mobile termination rates (MTRs), and O2 warned it would damage the prepay market. Which it didn't, BT concluded.
MTRs are levied on your network when you call someone on a different network. Any mobile calls made on a BT landline also mean that BT has to pay the called network a certain fee. It's these fees that lead to UK's astronomically high mobile charges per minute.