Who’s Calling, a marketing and call-tracking company servicing car dealers, agree to this week to an acquisition by Vista Equity Partners, a private investment firm in California, in a deal expected to close in September.

Who’s Calling, founded in 1998 by Lonnie Benson, was the first company to offer a call tracking device that allows dealers to measure the effectiveness of their advertising campaigns.

Dealers purchase 1-800 phone numbers from Who’s Calling, affix them to various campaigns; and using the company’s software, track how many phone calls are generated by each campaign.

Additionally, the software allows dealers to capture information about the parties calling, and integrate it into their dealer-management computer systems.

The product was a big hit with car dealers early on, aided by an aggressive marketing effort that included the handing out of 10,000 blue balls in 2001 at the National Automobile Dealers Assn. convention, along with boisterous parties at subsequent conventions.

Last year, Who’s Calling obtained the ability to track the effectiveness of online advertising when it acquired ClickPath, a Sacramento, CA-based firm.

Rumors about a potential sale of the Seattle-based Who’s Calling have persisted for several years. The firm has gone through a number of CEOs while developing new customer-relationship services for dealers and other industries, in an attempt to distance itself from competitors such as CallCommand, Call Source and CallBright.

According to the Seattle Post Intelligencer, Vista, which is one of the firms involved in Universal Computer Systems Inc.’s acquisition of the Reynolds and Reynolds Co. (both dealer computer technology vendors), is paying $55 million for Who’s Calling.

The deal means Who’s Calling and CallBright now have a connection to the same parent as UCS acquired CallBright last year.