Marchex today announced a new technology that brings its call analytics and attribution to unchartered waters: display ads. Known as Marchex Display Analytics, it claims to track 98 percent of calls unseen by traditional call analytics; and to reduce cost per conversion for display campaigns by 45 percent.

You may be thinking that calls can currently be tracked and attributed when launched from a display ad, which is true. But this can be limiting, given that display is more of a branding and awareness medium. It turns out that display ads don’t stimulate direct calls, especially when compared with more intent-oriented formats like search.

But they still have a notable impact: They reinforce brand awareness which is influences and drives calls subsequently.  In fact, only one in every 500,000 display impressions will launch a call. However if you expand the time window to two weeks after the impression, the odds improve to one in every 8,000 impressions.

And that’s where Display Analytics comes in. It goes beyond “last click” attribution commonly practiced, to instead ID calls placed at a later time. To do this, Marchex goes beyond common industry practices like tracking numbers. This is key because the subsequent call — days later — will often use a different phone number.

To do this, Marchex is using a complex system of attributing the initial impression to the subsequent offline call. That can involve caller ID’s and other data it’s incorporating as identifying factors. Marchex has a leg up here, given a robust database developed over years of connecting and tracking 300 million annual calls.

“In the Marchex Audience Graph we have a retroactive matching capability,” Marchex Senior Director of Product Engineering Adarsh Nair told us in a briefing yesterday. “We have 300 million calls running through our platform annually from 100 million uniques. we’ve been able to create a table to compare online and offline identity.”

Overall, the new capability opens opportunities in advertiser verticals where there’s an overlap in the venn diagram between high display spend, and high customer acquisition via inbound phone leads. This will mean going deeper in some verticals, and breaking new ground in others.

“Auto could be a big category as well as travel, financial and telco,” said Nair. “All these channels have a huge amount of their revenue coming from inbound phone calls. Wherever calls are a big sales driver, those are the verticals where we see opportunity.”