Regardless
of the media type, all transmissions would be packet data, and signaling would be SIP.
This is the future direction of IMS.
This is not as far off as some might think. It is possible we may see implementations
of SIP-enabled handsets in the very near future, which will only serve as a major incentive
for operators to move rapidly to an all-IMS environment. With support for packet
data and SIP network-wide, many elements and systems can be completely eliminated
from the network.
Figure 2.7 The CDMA network and packet domain
MSC PDSN
MSC
BSC
AN
Node
A
Node
B
Node
A
Node
B
AN
PCF
VLR
HLR
BTS BTS BTS
Other
network
Moving from Legacy to Convergence 55
Of course, this is still talking about an ideal world. There are many back office support
systems that will have to transition, because it is simply not possible to cut the cord
overnight and toss these systems out of the window. The entire business of the operator is
based on many of these support systems, so throwing them away is out of the question.
Likewise development is still lacking for many of these systems that support IMS.
For example, the entire area of billing is still being defined and refined. Operational
support systems (OSSs) are moving in this direction quickly, yet they have a different
view today than what operators may need going forward as their business models
change.
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