Carphone Warehouse has revealed robust mobile phone sales, but provided a weaker-than-expected outlook and growth in broadband customers.

Carphone Warehouse expects pre-tax profits to be between£215 and£220 million for the year to March 31. Analysts had forecast profits would come in at between£220 and£225 million.

The number of mobile phone customers at Carphone Warehouse rose 12 per cent to 2.7 million in the three months to March 31, more than previously expected. However, the broadband division added only 109,000 customers, compared with an expected 128,000.

The retailer said 67 per cent of its 1.8 million customers are now “unbundled” – where landlines are transferred from BT to Carphone Warehouse’s network to enable it to provide broadband services. It said it has just 8,000 customers that remain on BT’s network.

Carphone will spend a further£85 million on telecoms network infrastructure in the coming year to help bolster profits.

Chief executive Charles Dunstone said: “We anticipate a year of considerable progress. Although we are mindful of a tough consumer environment, we see significant opportunity to evolve our retail model to address the opportunities of a changing market.”

Carphone plans to open 120 stores during the year, as well as relocating about 50 stores to bigger premises.

It also expects to accelerate its Best Buy Mobile roll-out in the US, where Dunstone said progress “continues to be very encouraging”.