Home > Application
Areas > IMS
What You Need – Ready
Today
The standard AdaxGW performs the Signaling Gateway function to enable
voice calls between IMS and PSTN users.
IP Multimedia Subsystem, IMS, is causing quite a stir in
the communications industry. However IMS is more than just
the latest ‘buzz-word’. It has been at the centre
of a number of standard developments, including those for
SIP based services, and offers a cost-effective solution
for fixed and mobile convergence.
As with any new technology, there have been many new products
launched, all making great claims about what they do and
why they are necessary to make IMS happen. This has been
particularly true with regard to the interworking of IMS
and Public Switched Telephone Networks (PSTN). How do you
separate the reality from the hype?
Of course the products you really need will vary from network
to network, and be dependent upon such factors as the interfaces
already deployed within the network. However it is clear
that to be successful, IMS has to connect as many users as
possible. As the majority of users continue to use fixed
line telephones and cellular phones, the IMS network must
interwork with the PSTN to support basic voice calls. This
interworking needs to take place at both the user plane and
the control plane. It is the exchange of the signaling information
at the control plane that can be over complicated in some
networks and lead to confusion about what products and functions
are really necessary.
The control plane interworking is the job of the Media Gateway
Control Function (MGCF) which performs the mapping to and
from the SIP signaling and the ISUP. When a SIP session request
is received by the MGCF it performs the protocol conversion
between SIP and ISUP and sends the converted request to the
PSTN via the Signaling Gateway. The Signaling Gateway performs
the protocol conversion at the transport level and does not
interpret the ISUP or BICC messages. The Signaling Gateway
is just one example. Other ‘Gateway’ functions
within the IMS world that will emerge as the networks develop
will include security screening and border control.
IMS provides a cost-effective solution to Fixed and Mobile
Convergence but at this stage it seems best, wherever possible,
to try and avoid a large investment in new infrastructure
equipment. That is where the use of standard network building
blocks, such as the AdaxGW Signaling Gateway plays a crucial
role today. In future, the border and security screening
functions will ensure that IMS remains a cost-effective option
and reliable solution for Fixed and Mobile Convergence.
For further information on the AdaxGW click
here
|
