eBay will begin to sell radio advertising time through its auction site thanks to a partnership with Bid4Spots, which holds inventory from 2,300 radio stations in the top 300 markets.

The auction site typically offers unsold ad inventory, according to Bid4Spot's website.

The radio spots are available through the eBay Media Marketplace, the same section where advertisers can purchase television airtime as well. However on the television side, it has seen little use.

Only Oxygen participates in the program, as others have taken issue that they were not consulted before the site was launched. By adding radio spots, the company hopes to coax media companies into taking part.

Buying radio airtime will not work the same as a standard eBay auction. Instead, a bidder (the advertiser) will say what they are willing to pay, and in turn, the sellers (radio stations) make offers to the bidder.

Radio spots offered on the eBay Media Marketplace are the same as what is offered on Bid4Spots. Those registered with Bid4Spots can choose to use eBay's offering or stick with the old site.