It
would also make administration much easier, as the database changes would not have
to be replicated many times. This of course would require communications between the
switches and the database.
To facilitate these communications, a new control protocol was developed called
Signaling System #7 (SS7). SS7 (or C7 as it is often referred to in countries outside the
U.S.) is used by switches to send information about a telephone call to another switch
prior to connecting the trunk and routing the call over that trunk. It allows switches to
communicate to one another the requirements for the telephone call, and it also allows
specific services to be identified prior to routing the call.
The IN and SS7 also support databases in the core network for providing additional
instructions for treatment of a call. These databases have become especially important
in wireless networks that rely heavily on the SS7 and the IN. For example, the database
used by wireless networks to store information about their subscribers is referred to
as the Home Location Register (HLR). The HLR is a central function in any wireless
network and is accessed through the IN using the SS7 protocol.
Number Portability is another critical function that relies on the IN and SS7. Number
Portability would be impossible without the IN and SS7. The list goes on and on, and
includes many features and applications we take for granted today.
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