Methods and systems for deterring spam on a communication medium are disclosed. Call traffic on the communication medium includes IP telephone calls, IM™ messages and other IP calls. The method includes detecting a call with a user device for accessing the communication medium, such as an IP telephone, a computer, etc. A signaling message associated with the call is accessed and compared with information relating to identities that correspond to originators of spam calls sent over said communication medium, which is stored in a repository associated with the communication medium, such as a dynamically updatable database. Where no match is found between the signaling message and the stored spam call identity information, the call is routed to the user. Where the signaling message matches any said spam call originator identity information however, the call is deterred from being routed to the user.