Verizon, the largest US telephone company, has reported Q1 revenue growth.

For Q1, Verizon’s net income fell 50.2% to $1.19 billion, while sales grew a modest 3.9% to $17.13 billion.

The fixed-line carrier was boosted by its wireless division, the joint venture with Vodafone [VOD.L], Verizon Wireless. Wireless revenue jumped 21% to $6.16 billion, and the unit acquired another 1.4 million customers, up 66.5% from last year’s quarter.

Customers for the wireless division now totals 39 million users. This is twice as many as the 554,000 customer additions reported last week by Verizon’s closest mobile competitor, Cingular Wireless.

This means Verizon Wireless is still the number-one ranked US mobile operator, until the $41 billion merger of Cingular and AT&T Wireless Service completes later this year.

Verizon Wireless seems to be winning the business mainly at the expense of AT&T Wireless, which last week revealed that its exodus of customers had not stopped during the first quarter. It has also won customers from local carriers, as well as its parent group.

The dramatic success of the wireless unit is in contrast to the pressure that Verizon is coming under with its local-phone unit, which is losing business to long-distance and cable operators.

Verizon’s local lines fell 510,000, or 4.3%, to 55 million after some customers opted for phone service from cable companies, which sell telephone calls along with cable-TV and web access via cable modems. These schemes have added to the overall pressure on US carriers, as customers continue to abandon telephone lines in favor of emails or mobile phone calls.

Verizon and other regional-phone companies are trying to slow defections by trying to persuade local-phone customers to buy packages that typically include wireless and long-distance calls, as well as high-speed Internet access. However, it appears to be a losing battle: the decline in local lines has been reflected across the entire US telco landscape with SBC Communications [SBC] and BellSouth [BLS] shedding a combined 600,000 lines in the first quarter.

This article is based on material originally published by ComputerWire