What you need to successfully import call conversions

Imported Call conversions go beyond call length and measure the true value of a paid call from mobile click to call ads on the website. It is possible to distinguish various customer actions on a website that is valued differently. With insights gathered from imported call conversion it is possible to optimise keyword bids to drive more valuable calls using the target ROAS automated bidding.

What you need to successfully import call conversions
You only need to collect three pieces of information to import call conversion data into AdWords:
1. Caller phone number (Caller ID)
2. Call start time
3. Call length
This data will remain secure and privacy-safe for your customers, and serve as the key to match conversions back to the AdWords calls that drove them. Conversions will be attributed down to the keyword-level to help you determine which parts of your campaigns drive the most valuable call conversions and where you should be investing your ad spend.

Article source: https://adwords.googleblog.com/
Target ROAS: https://support.google.com/adwords
Image source: http://mobilemarketingengine.com/