An AIS identity mismatch is a conflict within transmitted identifiers or between AIS data and the observed or recorded vessel. This occurs when static fields such as MMSI, call sign, name, or IMO number are incorrect or duplicated.
For example, reports from vessels using the same MMSI can appear as one target jumping between positions on a graphical display. The USCG guidance records that invalid or duplicated MMSIs occur in this manner.
AIS can assist identification by name, call sign, ship type and navigational status, but received accuracy is only as good as the transmitted information and faulty input can mislead other vessels.
The simplest check on own-ship transmitted identity, position and movement information is to contact another vessel or shore station.
