Vodafone's US partner Verizon says first-quarter profits jumped 9.8%, driven largely by rising mobile income from text messages and wireless internet browsing.

Net profit climbed to $1.64 billion (£823.6 million) from $1.5 billion a year earlier. Sales were up 5.5% to $23.8 billion.

Verizon and Vodafone are big winners as customers switch from home-phone lines to wireless devices exclusively or to voice plans offered by cable TV firms.

The company added 1.5 million mobile users last quarter. Revenue from wireless data services such as video and text messaging climbed 49% to $2.3 billion. The average monthly mobile spend per user was $51.40.

Verizon's mobile-phone customers now spend $11.94 a month on text and picture messages, web browsing and ringtones, up 33% from a year earlier.

The results justify chief executive Ivan Seidenberg's strategy of shedding businesses to focus on wireless and a new fibre-optic network that offers faster internet connections and TV service.