A method, system, and computer program product for call flagging using shared call logs are provided in the illustrative embodiments. A determination is made that a phone call should be flagged as undesirable. In a call log in the device, a call entry corresponding to the phone call is selected. The call entry is modified to form a modified call entry, the modified call entry comprising an annotation, the annotation describing a reason for flagging the call as undesirable. A sharing rule is configured relative to the modified call entry. The modified call entry is sharing selectively according to the sharing rule with a subset of a set of social contacts of a user of the device on a social network.