If you were worried that the free domestic voice calls Google has offered through Gmail in the US and Canada were going to go away when 2012 ends, fear not — the company has just announced that its free calling offer will be extended through the end of 2013. Google started offering this feature back in August of 2010, and quickly extended it through 2011 and then again for 2012. We can't say we're surprised that Google is keeping this deal going, but we're happy about it nonetheless — it's one of the more underrated and underexposed features that Gmail offers. For those that want to make international calls, Google says it is continuing to offer "insanely low rates" for reaching out to those abroad.