Yesterday, Google announced a new feature to allow advertisers to track conversions via phone directly with call in phone numbers that forward to your main office or business.
Google launched "website call conversions" a tool that dynamically inserts a Google forwarding number on your website that measures the calls made by these customers. It is basically phone tracking numbers that track conversions from the click, Google offered this via the search results ads but not on your web site directly, now Google is giving you a way to track it on your web site.
It is available for U.S., Australia, France, Germany, Spain, and the UK only. You need to insert the snippet of code on your desktop or mobile website and a unique Google forwarding number will be generated for each AdWords ad click. These numbers will continue to display for up to 90 days to capture future call conversions. To ensure this experience is seamless, you can customize the look and feel of these numbers to match your website, including: color, font, and size.
They do cost money but you can use bidding methods such as Target CPA or Target ROAS.
Forum discussion at Google+.