/mcpInvalid message error received The typical scenario is an invalid message was received. 95 CC_CAUSE_INVALID_MESSAGE Indicates an invalid message event. Mandatory IE missing error Typical scenarios include: Mandatory Contact field missing in the SIP message. • The Session Description Protocol (SDP) body is missing. • 96 CC_CAUSE_MANDATORY_IE_ MISSING Indicates that the equipment that sent this cause code has received a message that is missing an information element (IE). This IE must be present in the message before the message can be processed. Message type nonexistent or not implemented The typical scenario is that message-type information is missing. 97 Indicates that the equipment that sent this cause has received a message which is missing an information element that must be present in the message before the message can be processed. Message not compatible with call state or message type nonexistent or not implemented Typical scenarios include: ISDN protocol mismatch • ISDN state machine violation • 98 Indicates that the equipment that sent this cause has received a message such that the procedures do not indicate that this is a permissible message to receive while in this call state. An information element or parameter does not exist or is not implemented The typical scenario is an element mismatch. 99 Indicates that the equipment that sent this cause has received a message which includes information elements or parameters not recognized because the information element or parameter names are not defined or are defined but not implemented by the equipment. Invalid IE contents error The typical scenario is a SIP contact field is present, but the format is bad. 100 CC_CAUSE_INVALID_IE_ CONTENTS Indicates that the equipment that sent this cause code has received an IE that it has implemented. However, the equipment that sent this cause code has not implemented one or more of the specific fields. The typical scenario is an unexpected message was CC_CAUSE_MESSAGE_IN_INCOMP_CALL_STATE Indicates that a message has been received that is incompatible Message in the invalid call state 101