Viber is Location-Aware:

How about sending your friends your present location? Viber also has this fanatastic feature, and as always, we have kept it simple.  Share your current location with your contacts so that they will know from where your message was sent. When sharing your current location, it will be attached to every outgoing message.  And of course your privacy is most important to us, so this feature can be enabled or disabled by simply tapping the 'location' button that has been added next to the input box.

When you select the little icon in the text window, it will highlight, and thus send your present location to the recipient. To stop sending your location, simply tap the icon again so that it is no longer highlighted.

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