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In addition an alternate version of the AeGGW is deployed in the network which does
not utilize the GSGW for those AES that do not support a VPN.
184.108.40.206 VoIP Gateway
The second voice channel is provided by using Voice over IP technology over the air
interface. A standard COTS gateway is used in the ground infrastructure. Signalling
is sent over a 3G standard IP PDP primary context established at power on of the AES,
while the voice frames are sent over a 3G streaming IP PDP secondary context which
is set up during call establishment. Both the standard and streaming context use the
same priority mechanisms as used for the prioritized IP service. The VoIP gateway is
also used to implement number translation. It is further described in Section 3.3.5.
3.2.4 CNP infrastructure
The Communications Network Provider (CNP), see Figure 3-3, provides the ground
infrastructure component for voice, ACARS, ATN/OSI and IP services to the ANSPs
and airlines. The CNP normally contracts with the airlines and ANSPs for the service
i.e . the business model is Inmarsat sell satellite air time at a wholesale level to the
CNPs who in turn sell the service at a retail level to ANSPs and airlines. The CNP
provides the end user ground connectivity and interacts with ground hosts via standard
communication interfaces. ARINC and SITA are CNPs.
For ACARS traffic, the CNP provides ground network connectivity, ACARS processing
and internetworking. The CNP establishes and maintains the connectivity to the
AeGGW for each ocean region. This connectivity provides the means to communicate
with aircraft logged onto SBB. CNPs not only provide the end users a path to
communicate with an aircraft, they also provide the management, formatting and
routing of the ACARS traffic. The aircraft communicate with the CNP Processor for
transmission and reception of ACARS messages using protocols specified in AEEC
specifications 618 and 620. The CNP Processor performs the ACARS protocol
handling functions, including the formatting, routing, and internetworking functions. In
some cases, the CNP Processor executes the message re-assembly function to
reconstruct multi-block ACARS messages. The routing function uses the destination
addresses derived from the ACARS messages for data transfer to the ground. The
internetworking function is used to exchange ACARS messages between CNPs in the
case where the ground host and the aircraft use a different CNP, as described in
Section 1.3 of the main body of this document.
For ATN/OSI traffic, the CNP provides ground network connectivity and
internetworking. The CNP operates ATN/OSI ground-ground routers to route traffic
The CNP infrastructure for voice allows authorized ground users to establish secure
voice calls with aircraft by the use of Caller Line Identification (CLI) and PINs. The
infrastructure allows the ground user to communicate with the aircraft at different call
priorities, as defined in Section 3.3.5.
For Prioritized IP service, the CNP provides the required ground connectivity,
management, and routing of the traffic to and from the aircraft.
LOGICAL SYSTEM ARCHITECTURE
Figure 3-11 shows the SBB logical architecture. The air interface, known as IAI-2
(Inmarsat Air Interface 2), is bespoke and is designed to maximize the performance
and capacity of the satellite. Above the air interface are standard 3G protocols and
these deliver 3G bearer services as well as administrative access functions. 3G bearer
services are both packet switched (PS) and circuit switched (CS), and conform to the
3G specifications. Gateways are used to provide additional services. A security
gateway provides a VPN for the use of the ATN/OSI service, the Enhanced ACARS
service, and the Enhanced PS Voice service. The aero gateway provides ACARS and
ATN/OSI services. A Voice over IP Gateway provide a ‘second voice channel’.
The CNP ACARS infrastructure provides the mobility management function and selects
between different ACARS services (VHF, satellite, etc.). The CNP ATN/OSI
infrastructure provides connectivity to ANSPs and ground/ground routers. The CNP IP
infrastructure provides connectivity from the Inmarsat Meet Me points and the ANSP
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