Sprint, the third-biggest US mobile operator and 80 per cent owned by SoftBank, reported net subscriber losses of 360,000 for the quarter. Analysts had only expected losses of roughly 313,000 on average.
By comparison, Sprint’s biggest rival, Verizon Wireless, added 927,000 subscribers in the quarter, and number two US mobile provider AT&T added 363,000. Smaller rival T-Mobile US is due to report results 5 November.
Sprint said it suffered from service problems in the quarter due to a massive network overhaul as well as the expected loss of corporate customers due to the June shutdown of its iDen network, which was used mostly by business customers.
Chief executive Dan Hesse told analysts on a conference call that customer defections would continue to be at high levels into the middle of 2014, when the company expects to complete the bulk of the network overhaul.
Sprint reported a third-quarter profit of $383m (£238m), compared with a loss of $767m in the year-ago period, before its SoftBank and Clearwire deals.
The company said the latest quarter was helped by a one-time, non-cash, $1.4bn gain, net of taxes, related to its previously held investment in Clearwire.
Revenue fell to $8.68bn from $8.76bn.
Sprint still expects 2013 adjusted earnings before interest, taxes, depreciation and amortisation (Ebitda) of between $5.1bn and $5.3bn, including the dilutive effects of the SoftBank and Clearwire transactions.