Pay per call advertising is picking up some serious steam. So much so that I am currently writing a full report on the subject for release soon.

Pay per call, like its better known cousin pay per click, is advertising that generates a billable event only when the reader of the ad does something – in this case, makes a phone call.

For certain types of local small business advertisers this form of advertising is going be huge. Every major search engine has made a local search play. It only makes sense that they are going to move into other devices like your phone too.

Local searchers and local advertisers may find pay per call the perfect marriage of high-tech (Internet search) and low-tech (the phone.)

Think about this. You search online or through Google Local on your phone for a beauty salon in a town your are visiting. Up pops an ad with a local phone number – you call up the place, make an appointment and the salon gives Ingenio (the current pay per call leader) a buck for the call. (This will end up in Google Talk, AIM, Skype and other VOIP apps too.)

With pay per call you don’t even need a website. (it pains me to admit that) Any business can buy pay per call ads and start getting calls while sitting in their truck on a job site.

The search engines are going to jump on this in a very big way. They have already found that businesses are eager for this form of and will pay much more for it because the conversion rate is often as much as ten times greater than pay per click.

The key as with all forms of advertising will be who gets the best ad distribution where people are searching. Google has not officially weighed in. But, they are testing variations.

This is an emerging game at the moment but here are the players for now
Ingenio – clear leader and sewing up search on the major engines – AOL, Local.com and testing on Yahoo
Jambo – Good looking interface – building their own ad network
MIVA– distributes ads through publisher network
VoiceStar – Includes interactive sales tracking and custom IVR