ePort, an online ad platform for TV spot buying, has crossed the 500 station mark, reports Mediaweek.

507 stations have registered to participate in the program, which allows advertisers to buy spot placement on TV. Those stations hail from 176 markets.

The first phase of ePort's new model goes live later this month. Buyers will be able to electronically place orders with stations for the first quarter of 2008.

Other rollouts for the platform are planned for March of next year and include segmented invoicing and more finely-tuned buying.