Message Direction and Scope

We can distinguish Q.931 messages by their direction and scopeā€”see Fig. 10.3-1. Network-to-user messages (a,c) are sent from a local exchange to a TE, and user-to-network messages (b,d) are sent in the opposite direction. In

Figure 10.3-1 Classification of Q.931 messages by direction and scope.

addition, we speak of local messages and global messages. A local message (a,b) is of significance only to the TE that sends or receives the message, and its local exchange. A global message (c) is a message, sent by a TE, that has significance for its local exchange, and for the distant TE. Global messages are transferred across the network, and delivered (d) to the distant TE.

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