Having drawn a line under its struggles in the UK through a joint venture with France Telecom’s Orange, Deutsche Telekom now faces a bigger challenge: sorting out its troubled mobile operation in the US.

T-Mobile USA, long a source of growth for DT, is struggling to keep up in a vicious price war, as last quarter’s fall in revenues shows. One idea is that DT, the fourth-biggest US mobile operator by subscribers, might join with lossmaking Sprint Nextel, currently third. This would be similar to what DT did in the UK. Yet even if such a deal survived the regulators, incompatible technologies would make extracting synergies difficult. Real benefits may not appear until Sprint’s 4G strategy begins to bear fruit, which could take several years. Meanwhile, Bernstein reckons that the more stable pricing brought about by consolidation would benefit DT’s rivals, such as Verizon and AT&T, as much as itself.