From SS7 Message to IP Packet

The following figure and description show how SS7 messages are encapsulated and sent over an IP network to a host in another network.

Figure 2-4 Transmitting an SS7 Message using IP

1. A signaling point issues an SS7 message, unaware that there is IP signaling in the network. The message contains Link Status Signaling Units (LSSU), Fill In Signal Units (FISU), Final Signal Units (FSU), and Message Signal Units (MSUs).
2. The Signaling Gateway receives the SS7 packet and encapsulates all necessary SS7 information into the data section of the IP packet. The packet includes the data, source and destination IP addresses.
3. The packet travels across the IP network. The network is unaware that it is delivering SS7 data. There is no need to modify the routers or gateways along the way.
4. The packet is delivered to the Signaling Gateway on the receiving network. The SS7 information is recovered from the IP packet.
5. A well-formed SS7 packet is sent to the destination Signaling Point.