If you are not using HulloMail just yet, then you probably should. It closely resembles Google Voice's voicemail or iPhone's Visual Voicemail, except it takes it few steps forward with some really smart features. That's not the point, anyway. The killer feature for me is that it can forward all your calls (not only missed ones) to a voicemail so your phone essentially never rings, but you receive notifications about calls all the same via push notifications and email. This means you cut out all non-essential calls but still can react on those which are important.
This is especially a killer feature if you want to use a local SIM card of the country you're going to but still want to keep an eye on who's been calling you.