Google announced today that it will add trackable numbers to AdWords campaigns. Known as AdWords Call Metrics, this will offer advertisers analytics on call activity such as total calls per campaign, origin, time of day and duration.

The underlying technology will be Google Voice and unique numbers will be assigned to businesses. These will be inserted in their ads, connected to their actual phone numbers and tracked. Numbers will show up on desktop and smartphone searches and take the following forms:

Top SERP Ads

Right Margin SERP Ads

Mobile Ads

Unlike many call tracking programs, there won’t be a premium placed on calls generated or any additional cost to advertisers. This is similar to what Google did with its mobile pay-per-call ads.

The difference — besides a Google Voice unique tracking number — is that it now has a more robust back-end analytics dashboard so that advertisers get a clearer ROI snapshot through AdWords. From Google’s blog post:

Zac Stafford, Senior Search Strategist at Nina Hale Search Marketing in Minneapolis, MN, recently discovered that this was true for his client, modern furniture retailer Room & Board. Stafford saw some encouraging results as an early beta tester of AdWords call metrics, a new feature that automatically includes a unique phone number in your ads to measure the calls that you receive from AdWords.

“By cross-checking our call metrics reports with our sales records, we saw that half the people who called the toll free number in our ad purchased online but the other half purchased in a store. Before using call metrics, we determined our ROI just by looking at the online sales numbers. Now we have proof that online search ad campaigns drive in-store purchases.”

As we argued with Google’s mobile pay-per-call program, this will eventually integrate more discrete pricing. For now, Google is keeping pricing simple and free in order to lower adoption barriers, and also positioned it as a “value add” or retention tool for AdWords itself.

Additionally, it’s a good feedback tool for advertisers to improve and iterate their campaigns. In other words, like there is an art to generating clicks from AdWords copy and geotargeting, different ad groups can be devised that prove effective in driving calls specifically.

This is a feedback loop that could take some time to develop, and likely only see traction among savvy AdWords advertisers or agencies. But it’s nonetheless an interesting concept that will develop. Google is getting the ball rolling now. For more, here’s the promo video: