signalling information field (SS7) (SIF)

The Signalling Information Field (SIF) is a variable length data field within the Message Signal Unit( MSU) of an SS7 message.

Structure of the Message Signal Unit (MSU)

The SIF data field varies in length from 8 octets to 272 octets and is used by all Level 4 protocols.

This data field contains the routing labels and the signaling information such as the Service Switching and Control Points( SSCP), the Transmission Capability Applications Parts( TCAP) and the messages for the ISDN User Part( ISUP).