INAP
Intelligent network application part protocol
© Yiqun Xu & Zhiping Duan
March 15 2002
Architecture of IN
Switch
Routing
Announcement
Simple Tone
Generator(IP)
Unit
Call processing
Digit Analysis
Switching fabric
Advanced
QueryFeature
processing
processing
(SSP)
SCP: Service Control Point
SSP: Service Switching Point
IP:
Intelligent Peripheries
IN:
Intelligent Network
IP
Announcement
Unit and more
SCP
Advanced Feature
processing
Overview of INAP(1)
intelligent network application part protocol
• Vendor independence to Telco
• Open Interfaces
Service Logic
Routing database
INAP
DB
SSF
Switches enhanced
INAP
to support IN
(interface with SCP and IP)
• Rapid, cost effective, and
lower risk service deployment
SCF
Voice
INAP
SRF
• Ability to design and customise
new services
Overview of INAP(1)
intelligent network application part protocol


1. the main purpose of INAP is to define the information-flow format
between different function entities
2. Information flows of the INAP can be defined between:SCF and
SSF ,SCF and SRF, SCF and SDF which are located in different
location, so that the whole service logic can be executed in the
distributed system.
Relationship between different entities
–
–
–
–
Service Switching Function (SSF)
Service Control Function (SCF)
Specialized Resource Function (SRF)
Service Data Function (SDF)
Information
Flows between two FEs consist either of a
request/response pair or of a request alone.
Relationship between SCF - SSF


is established either as a result of sending a request
for instruction to the SCF (SSF->SCF), or at the
request of the SCF for initiation of a call(SCF>SSF)
is normally terminated at the request of the SCF.
The SSF may also terminate the relationship
(e.g. in error cases).
Example:
Initial DP
IF is generated by the SSF when a trigger is detected at any DP in the
BCSM, to request instructions from the SCF.
Relationship between SCF -SRF



is established by the SRF sending an “assist request
instructions from SRF” to the SCF. The SCF can now instruct
the SRF to perform some interaction with an end user .
is terminated by the SCF.
The establishment of this relationship must be preceded by
the establishment of a relationship between the SCF and SSF.
Example:
PromptAndCollectUserInformation
After SRF receive the instructions from SCF, SRF will be used to
interact with the user (play announcement and collect user’s input)
Relationship between SCF-SDF
is established at the request of SCF when
SCF requires to retrieve or modify some
data contained within the SDF
 is terminated by the SDF

Note: SDF is a remote database application, not the database attached
with SCP.
Example:
AuthenticateResult
1. SCF is asked to retrieve or modify data within SDF
2.SDF sends information flow to a SCF to inform SCF of the
authentication result
Overview of INAP(2)
intelligent network application part protocol


INAP is an application-layer protocol used in Intelligent Networks.
This protocol runs on top of TCAP and is deployed using SS7 (or other
signaling environments)
I
N
A
P
M
ISUP
A
P
TCAP
SCCP
MTP
INAP Protocol Architecture
---Single Interactions
(The SAO represents the SACF plus INAP to be used over a single interaction between a pair of PE’s.)
Application Process
SAO
S
A
C
F
ASE’s
TCAP
SCCP
MTP
SAO: Single association object
SACF: Single association control
function
ASE: Application service element
INAP: the collection of specifications
of all in ASE’s
TCAP:transaction capabilities
application part
SCCP: service switching and control
point
MTP: Message Transfer Part
INAP Protocol Architecture
---Multiple coordinated
(interactions will be happened among several SAO’s, MACF will be offered to provide a coordinating
function among those SAO’s, each of which interacts with an SAO in a remote PE.)
SAO: Single association object
SACF: Single association
control function
Application Process
MACF
SAO
SAO
S
A
C
F
ASE’s
S
A
C
F
TCAP
MACF:Multiple association
control function
ASE’s
ASE: Application service
element
TCAP
INAP: the collection of
specifications of all in ASE’s
SCCP
TCAP:transaction capabilities
application part
MTP
SCCP: service switching and
control point
MTP: Message Transfer Part
SACF/MACF rules
Stipulate the format of operations’ sequential/parallel execution:


Operations performed in parallel are to be
included in the same message(case A)
Operations performed sequentially are to be
controlled in two separate message(case B)
For example, charging operations may be synchronized with
other operations and CallInformationRequest operation
may have to wait for CallInformationReport operation.
800 Service (example using INAP)
PSTN
4. Rings the callee party
1. Dials 800#
SSP/SG
3. SCP find the real
number in DB and inform
SSP to reach callee party
INAP
INAP
2. Launches the 800
Service
DB
SCP
Evolution of INAP(1)
The evolution of INAP depends on
the development of IN Capability
Set.
Evolution of INAP(2)
INAP for IN CS-1
Q.1208: general rules for INAP ; Q.1218: refined (CS-1R) as described
Interface:
»
»
»
»
Service Switching Function (SSF)
Service Control Function (SCF)
Specialized Resource Function (SRF)
Service Data Function (SDF)
Relationship :
» SCF-SSF
» SCF-SRF
» SCF-SDF
Evolution of INAP(3)
INAP for IN CS-2 (Q.1228)
Interface
»
»
»
»
»
Service Switching Function (SSF).
Service Control Function (SCF).
Specialized Resource Function (SRF).
Service Data Function (SDF).
Call Unrelated Service Function (CUSF).
Relationship
» SCF-SCF
» SDF-SDF
» SCF-CUSF
Why INAP:



To define message format between different
function entities in order to execute the whole
service logic in the distributed systems.
To support SIBs when they are mapped into DFP
……
Operation, Error and Data type
……

ApplyCharging procedure
ApplyCharging ::= OPERATION
ARGUMENT
ApplyChargingArg
ERRORS {
MissingParameter,
UnexpectedComponentSequence,
UnexpectedParameter,
UnexpectedDataValue,
ParameterOutOfRange,
SystemFailure,
TaskRefused
}
-- Direction: SCF -> SSF, Timer: Tac
-- This operation is used for interacting from the SCF with the SSF charging
mechanisms.

ApplyChargingReport procedure
ApplyChargingReport ::= OPERATION
ARGUMENT
ApplyChargingReportArg
ERRORS {
MissingParameter,
UnexpectedComponentSequence,
UnexpectedParameter,
UnexpectedDataValue,
ParameterOutOfRange,
SystemFailure,
TaskRefused
}
-- Direction: SSF -> SCF, Timer: Tacr
-- This operation is used by the SSF to report to the SCF the occurrence of a specific
charging event as requested by the SCF using the ApplyCharging operation .
Four kinds of operations
operation
1
FE
operation
FE
FE
FE
error
response
PromptAndCollectUserInformation: SCF inform SRF to
play announcement and collect user’s input, SRF
should return the result of this operation or error
message to SCF at the end of this action.
operation
2
FE
FE
error
ApplyCharging: SCF inform SSF begin to charge and tell SSF the
charging policy as well. If something is wrong, then SSF will
report this error to SCF immediately, or it will begin to execute
this action, and report the result to SCF using another operation
procedure “ApplyChargingReport” when the call terminates.
3
operation
FE
FE
response
4
operation
FE
FE
Activetest operation: SCF send Activetest to
SSF, if everything is ok, SSF will return
a response to SCF immediately, if
something is wrong, there should be no
any response at all. So this operation
only expects “successful result”.
Release operation
Continue operation
How does INAP work(1)
Alice
SCP
SSP
Bob
Dial an calling card access number
InitialDP
Invoke service
logic
PromptandCollec
tUserInformation
Play announcement and collect information
Return the result
ApplyCharging ;
Connect
Ring Bob and
Bob pick up
the hook
Alice and Bob are talking…
Tdisconnect ;
ApplyChargin
gReport
Release
Busy tone
Bob hands up
How does INAP work(2)



SSF send InitialDP to SCF and invoke the service logic.
Applycharging and Connect are sent to SSP in parallel.
Tdisconnect and ApplyChargingReport are sent to SCP in
parallel.
How INAP message transmit through SS7
I
N
A
P

M
ISUP
A
P

TCAP
SCCP

MTP
INAP operation and its
parameter should be put
within one component
INAP encapsulated as
component by TACP and
then transmitted by TCAP.
One TCAP message can
transmit several components
at the same time
Interactions between ISUP and INAP

This interaction takes place in the CCF and SSF.
– • detection point processing in the CCF;
– • receipt of INAP operations in the SSF.



ISUP: Supports the call control function. exchanges
signals between SSPs and establishes the voice
path between SSPs.
CCF: Handles all normal calls by providing the
processing and the control of call or connection
between network subscribers.
SSF: Acts as the interface between CCF and SCF
Why interaction happens?
SCP
SCF
OLE: Originating Local Exchange
INAP
DLE: Destination Local Exchange
SSP
SSF
Access OLE
Signalling
ISUP
CCF
ISUP
DLE Access
Signalling
T11103720-
Explanation of last slide



1. The signaling between SSPs are transmitted by
ISUP
2. Here we consider OLE and DLE as SSPS as
well.
3. If the SSF(located in OLE) have to invoke a
service which happens to locate in a SCP that
there is no direct link from the local SSP(OLE)
and that SCP, then interaction between INAP and
ISUP happens…
Where the interaction happens
The interaction between ISUP and INAP takes place
in the CCF and SSF:
• Detection point processing in the CCF
example:
T_Mid_Call
• Receipt of INAP operations in the SSF
example:
ActivateServiceFiltering operation: ACM
message or REL message will be sent with
different parameters.
Scenario: IP is separated…
ISDN/
PSTN
link
SSP
SSF and CCF
IP
SCP
SRF
MACF
MACF
S IN
A AP ISUP
C
F TCAP
ISUP
SCCP
Remote ssp
S IN
A AP
C
F TCAP
MACF
S IN
S IN
A AP A AP
C
C
F TCAP F TCAP
SCCP
MTP
SS No. 7
link
SCF
SCCP
MTP
SS No. 7
link
MTP
SS No. 7
link
SS No.7
network
Explanation of last scenario
SSP connect to remote SSP and IP via ISUP,
SCP can not deal with ISUP signal directly.
 There are 2 possibilities for SCP
communicate with IP: 1. transfer INAP
messages via SS7 directly. 2. Transfer INAP
message to SSP, and SSP send ISUP signal
to IP.

Scenario: IP attached to an assisting SSP
SCP
SCF
INAP
INAP
OLE: Originating Local Exchange
SSP
SSP
SSF
Access OLE
Signalling
ISUP
CCF
SSF
ISUP
CCF
DSS1 or
implement.
dependent
interface
IP
SRF
T11103750-99
Interaction between INAP and SIP

SIP, Session Initiation Protocol, is a new signaling
protocol for establishing real-time calls and conferences
over Internet Protocol networks.

SIP is also an application layer signaling system, with the
interaction between INAP and SIP, IP network can
communicate with traditional PSTN.

Mapping INAP messages/parameters into (sequences of)
SIP messages/parameters and vice versa.
Benefit of this interaction



The existing IN service can migrate to IP
telephony
IP architecture may borrow service concepts from
IN potentially
Unified Messaging
Service Deployed In IP Networks
SCF
SDF
INAP
SSF
SOFT
CCF mapping SSP
SIP Proxy Server
Extended
SIP Proxy
Server
SIP
Gateway
SCN
SIP User
Agent
IP NETWORK
Terminal
Terminating Call with INAP Interaction
SCP
Extended
Proxy Server
INVITE
From SIP server/user agent
InitialDP
Service
logic
INAP instruction
INVITE
CALLEE
IN service located in PSTN
Entities in Converged Network
Services
SCP
SCF
INAP
Service
Gateway
INAP
SSF
INAP AU
SRF
Voice
Path
INAP
Service
Switching Point
PSTN
SIP
SIP
RTP
SIP Proxy Server
VoIP
•Service Control Point (SCP) - SCP has
Services applicable for PSTN and VoIP
(SIP) networks
•Specialized Resource Function (SRF) SRF provides media resources
•Service Switching Function (SSF) - SSF
invokes the services on SCP for PSTN and
VoIP networks
•Service Gateway (SG) - SG interface
with SIP proxy server. SG has INAP AU
and the SSF functionality
•INAP AU - The INAP AU maps SIP state
machine to the IN call model
Reference
ITU-T Q.1218
 ITU-T Q.1600
 Interworking between SIP and INAP
 SIP/IN Interworking
 INAP Support of the SIP/SDP Architecture

Thank you!
Any question