Are Call Metrics enabled in your Google AdWords account? If so, there are some important changes related to pricing that are planned to happen on or after May 16, 2011.
New pricing for phone calls to Google forwarding numbers
Google will begin charging $1.00 USD per manually dialed call completed to your Google forwarding numbers. Manually dialed calls occur when potential customers who are using a desktop or laptop computer see your ad and dial the number shown.
Charges for calls from click-to-call ads on a high-end mobile device are not changing. Such calls continue to be charged as ordinary mobile search ad clicks. Learn more.
In the near future, calls to a Google forwarding number will be factored into Ad Rank calculations, which determine an ad’s position and cost per click. You’ll be able to influence your ad position by specifying a bid per call greater than $1.00 USD — similar to increasing your max CPC bid today.
For more details, contact your Search Discovery team.