RealNetworks plans to acquire South Korean mobile entertainment provider WiderThan in a cash deal worth around $350 million.

WiderThan, in Seoul, provides a range of mobile entertainment services, including ringback tones and games. The company's On Demand Music service offers licensed music for both wired and mobile devices, the company's Web site said.

RealNetworks said the acquisition of WiderThan will strengthen its entertainment offerings for operators. In addition, the deal will increase the reach of both companies by combining the strengths of both companies in North America with RealNetworks' business in Europe and WiderThan's operations in Asia, including South Korea.

RealNetworks expects to complete the acquisition during the first quarter of 2007. After the deal goes through, WiderThan will operate as a subsidiary of RealNetworks and the WiderThan brand will be maintained.

In July, WiderThan's US subsidiary was sued by TeleCommunication Systems (TCS) in the US District Court for the Eastern District of Virginia. TCS alleged that WiderThan infringed its patent for a technology that routes inter-carrier messages addressed using only the recipient's phone number.

WiderThan dismissed the allegation and pledged to defend itself against the charges.