Adwords call extension allows advertisers to include a phone number within their ad copies as shown here. But the use of Adwords call extensions can have an undesired effect on Adwords accounts in countries without Google call forwarding.
Google call forwarding is a feature of Adwords that allows Google to track calls driven by call extensions. It works by assigning and displaying a unique Google call forwarding phone number in place of the call extension number entered by the advertiser. Calls to the Google call forwarding numbers are then recorded by Google and then redirected to the advertiser’s call extension number. This allows Google to track such call as driven by an Adwords call extension. At present, Google call forwarding is only available in the US, UK, France and Germany.