The facilities connected to
the media gateways (MGs) under the control of the MGCF are managed as well on the
TDM side of the network using the SS7 protocol, and therefore the MGCF must be a
stateful entity.
Now that we have a basic understanding of how access to the network is accomplished,
we can start digging into the processes used to register.
Registration in the IMS Using SIP
This is probably a good time to talk about the difference between subscribers and subscriptions.
Keep in mind that throughout this book when we talk about subscribers
and/or subscriptions, the network cannot identify individuals. The network can only
register and authenticate subscriptions, which do not necessarily identify real people
(in other words, unauthorized individuals could register using someone else??™s subscription).
We will use both terms interchangeably throughout the book.
In order for the network to connect calls to a device, it must first know where in
the network to find the device, and how to route session control messages (SIP) to the
device. This is accomplished by forcing all devices to register with the network when
they are activated. This registration provides the network the information needed to
be able to locate the device, and route SIP messages to the device, as long as it remains
activated.
This also means that as the device changes locations and associated addresses, the
device must re-register with the network to provide its updated location information.
Pages:
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239