Cox Communications, the Atlanta-based media firm that has the largest share of the San Diego cable market, said it will discontinue its recently rolled out wireless cellphone service effective March 30.

Cox said the decision to stop offering its 3G service was based on “the lack of wireless scale necessary to compete in the marketplace, the acceleration of competitive 4G networks as well as the inability to access iconic wireless devices.”

The company had launched the service in San Diego a few months ago with a major advertising campaign. The service was also rolled out in Orange County, Santa Barbara and six other markets, the company said in a press statement Nov. 15.

Customers who signed up for the service will get a $150 credit on their bill for each wireless line disconnected. They’ll also be able to keep any devices with all early termination fees waived.

Cox said its television, high speed Internet, land line and commercial phone users won’t be affected by the decision to halt wireless service.

— Mike Allen