Garett Rogers has found an unreleased feature in Gmail that enable users to call contacts from inside Gmail. — “If my eyes are seeing correctly, it appears some users should have a "Call" button in their Gmail when Google Talk is connected — clicking this button opens up a new voice conversation with the selected user through Google Talk.  As of right now, we are still unable to place or receive incoming calls directly through Gmail — but I have a feeling that's is on the "to-do" list.”

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Source:→ ZDNET