By Kate Holton
LONDON, April 18 (Reuters) - Vodafone unveiled a raft of changes to its pricing model on Thursday, moving more towards an American-style system to help protect its income from technologies offering rival services over the Internet.
The changes are designed to deter customers from choosing popular "over-the-top" services such as Skype, What's App and Viber to message friends for free.
The world's second-biggest mobile phone operator said it would offer its Vodafone Red package across its 14 European markets, enabling customers to pay a monthly fee dependent on how much data they want to use, which includes unlimited calls and text messages for free.
By the end of the year, the British firm will also allow customers to take multi-device plans and family plans, which offer customers extra devices and extra family members at a discount to individual mobile plans.
The new pricing approach aims to simplify the billing process for customers who own smartphones, laptops and tablet computers and want to access the Internet on the go.
The changes also show the influence Vodafone's partnership with Verizon Communications is having on the British firm, as such data plans are more common in the United States.
The two groups have a joint venture in the U.S. called Verizon Wireless, the country's largest mobile operator, but speculation has mounted that Vodafone could exit the partnership to generate cash to invest in Europe.
Vodafone Chief Executive Vittorio Colao has said he has an open mind on keeping the stake, but he has repeatedly said the group benefits from its ties in the U.S., where the telecoms market is seen as more healthy than Europe, with higher margins as consumers make more phone calls and pay more for data.
Vodafone said in February that more than 2 million customers had signed up to its Red package in five countries including Britain and Germany.