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Feature F-1553 gives the IMG the ability to route a call based on the state of the 'M-bit' in the FCI (Forward Call Indicator) message that is sent in the ISUP IAM message. When an IAM message comes into the IMG, the IMG will parse the message. Depending on the value of the M-Bit, the FCI parameter will dictate how the call will be routed. See the Link in the Related Topics section below for more information.