Don't bother.

Cox’s ambitious plans to get into the cell phone business were already tempered by the cable company’s decision last spring to simply resell Sprint service under the Cox name.  Now it’s “game over” as the company today quietly stopped signing up new customers and will pull the plug on existing ones March 30, 2012.

Those customers already signed up for Cox’s “unbelievably fair” cell service will officially become Sprint customers next April.

In a confidential memo obtained by Engadget, Cox executives ultimately decided it didn’t make sense for the company to invest in a limited range 3G cellular network.

Cox’s plans to utilize the 700MHz wireless spectrum it acquired in 2008 for 3G-powered wireless service began to go wrong almost from inception.  The wireless business is increasingly in the hands of two super-sized companies, thanks to ongoing mergers and acquisitions.  That leaves smaller, regional companies at a competitive disadvantage unless they heavily discount service.  While Cox was contemplating its first 3G network, AT&T, Verizon, and Sprint were well on the way to launching next generation 4G service that would have left Cox behind.

Cox itself is a regularly-rumored takeover target, likely by Time Warner Cable.  No cable industry buyer has much interest in a cell phone service.  Shedding it could make the company more attractive for would-be suitors.

Engadget reader Sal Petrarca observed:

“I always thought it ironic when I [heard Cox’s radio ad asking customers] ‘You wouldn’t order cable from the phone company, would you?’ I guess no one is going to be ordering [cell] phones from the cable company now, eh?”