Google announced on Google+ that call extensions now support local forwarding numbers, so you can show searchers local numbers to them, which may increase the chances they will call your local business.
Google said, "starting today, ads with call extensions set up to use Google forwarding numbers can now show a local Google forwarding number, where available."
These local forwarding numbers will use the same area code as your business phone number, or a local area code for the same geographic region.
They only work for US based businesses.
To learn more about setting up these local numbers, see the help documents.
Forum discussion at Google+.
