We understand the need to contact those friends and family that may be calling you! If the number is showing Unknown and DOES show a phone number (so then just the name is unknown) you should be able to click on that in your call logs to call it back, however, if the number and name were both Unknown, the device would not know what number to call back. You could try dialing *69 (charges may occur) but with a fully unknown name and number this may or may not work.
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