2009年11月14日

Number Portability Overview (LNP, MNP, WNP, IMS-NP)

Number Portability Overview (LNP, MNP, WNP, IMS-NP) - Regulatory Service

1). NP and LNP Overview:

1-1). NP Solution for different networks:

§ Local Number Portability (LNP)

§ Wireless Number Portability (WNP) or Mobile Number Portability (MNP)

§ NP in IP network

§ NP in IMS and MGCF domains


1-2). NP Architecture and Provisioning Flow (N/A):

§ NPDB and NPAC (Number Portability Administration Center)

The Number Portability Administration Center Service Management System (NPAC) is operated by a third party and is the central arbitration, storage, and distribution point for all ported number information.

§ Service Order Administration System (SOA)

The Service Order Administration System (SOA) interface supports order entry, procedures for order concurrence, and order activation for new, modified or deleted ported number information.

§ Local Service Management System (LSMS)

The Local Service Management System (LSMS) receives ported number information from the NPAC and distributes the appropriate data to the network elements in the signaling network.


1-3). Type of Local Number Portability:

The database functionality to offer Portability for Geographic Numbers via Local Number Portability (LNP) in the fixed network

§ Geographic Number Portability – for location change

§ Service Provider Number Portability – for service provider change

§ Service Portability (e.g., 800 freephone service) – access to 2 DBs: NP-DB and Freephone-DB


1-4). Routing Mechanisms of LNP:

1. All Call Query (AcQ): The Originating Network receives a call from the caller and sends a query to a centrally administered NPDB.

2. Query on Release (QoR): The donor network releases the call and indicates that the dialed directory number has been ported out of that switch. The Originating Network sends a query to its copy of the centrally administered NPDB.

3. Onward Routing (OnR): The donor network checks the dialed directory number has been ported out, and use the new routing number to route the call to the new serving network.

4. Call DropBack: The donor network releases the call by providing the routing number. The Originating Network uses the routing number to route the call to the new serving network. (N/A)

5. Switch-based Call Forwarding Enhancement – forwarded thru new routing number (Like OnR - N/A)


1-5). Routing Number can identify

§ a Recipient Network

§ a Point of Interface (POI)

§ a Recipient Exchange

§ A Subscriber/ Access line / service

§ or a combination of any of the above.


1-6). In the PLMN networks: How to query NPDB, Routing Mechanisms of MNP

§ Mobile Number Portability (in the GSM/UMTS networks) or Wireless Number Portaility (in the cdma network)

§ IN Solution vs Signalling Relay via SRF Solution

§ Call-Related (e.g., Voice Call) and Non-Call-Related (e.g., SMS) for NP

§ Originating All Call Query

§ Originating Call Query on Digit Analysis (OQoD)

§ Terminating Call Query on Digit Analysis (TQoD)

§ Query on HLR Release (QoHR)

§ Direct Routing vs Indirect Routing


1-7). In the IP or IMS networks:

§ Number Portability in the IP or IMS networks interacted with PSTN / PLMN networks where numbers or services are non-ported or ported

§ NP in MGCF vs IMS domains

§ E.164 number vs URI for NP

§ ENUM-Based NP Solution: Using E.164 Number Mapping (ENUM) with updated information from NPDB

§ IM-SSF Solution: Trigger for IN/SCP NP Service

§ MGCF-based NP Solution in MGCF Domain: Using MGCF/SGW to query NPDB

§ TSF-Based NP in CSCF Domain: As an AS solution


1-8). Number Portability OV - Protocol

Access to portability corrected addressing services via SS7/C7, SIGTRAN, ENUM and SIP protocols.

§ Protocols: AIN, CAP, ENUM (RFC 4769), INAP, IS-41, ISUP, MAP/SRF, and SIP (RFC 4694).

§ Interfaces include: IP, SIGTRAN (M3UA) and SS7/C7 MTP3/MTP2 (T1/E1 links).


1-9). NP Addressing Method of Q.769 - NoA, CdPN, CdDN, NRN

1). Separated Addressing method

2). Concatenated Addressing method

§ Based on the ITU-T Recommendation Q.769.1, the call routing example described above shows one of the three methods that can be used to transport the Directory Number (DN) and the Routing Number (RN) in the ISUP IAM message.

§ The three methods and the enhancements in ISUP to support number portability are briefly described below:

a) Two separate parameters with the CdPN parameter containing the RN and a new Called Directory Number (CdDN) parameter containing the DN. A new value for the Nature of Address (NOA) indicator in the CdPN parameter is defined to indicate that the RN is in the CdPN parameter. The switches use the CdPN parameter to route the call as is done today.

§ CNP with Separated DN Addressing method, NOA=6 after query SCP

§ CdPN = NRN NOA = 6 and CdDn = B-DN NOA = 3

b) Two separate parameters with the CdPN parameter containing the DN and a new Network Routing Number (NRN) parameter containing the RN. This method requires that the switches use the NRN parameter to route the call.

c) Concatenated parameter with the CdPN parameter containing the RN plus the DN. A new Nature of Address (NOA) indicator in the CdPN parameter is defined to indicate that the RN is concatenated with the DN in the CdPN parameter.

§ CNP with Concatenated Addressing method, NOA=8 after query SCP

§ CdPN = NRN + B-DN NOA = 8


1-10). Number Pooling:

§ Number Pooling: Allows porting of blocks of numbers

§ Number Pooling is a method of Number Resource Optimization that is mandated by several State Commissions to conserve NPA-NXX resources


2). MNP and WNP Overview:

2-1). Mobile Number Portability OV (GSM/UMTS) – IN-based Solution

§ In a GSM network that supports the IN-based approach for Call Related MNP cases, each GMSC shall support at least one of these options below.

§ IN-based approach for Mobile NP architecture and call flow [refer to 3GPP 23.066]

There are two IN-based solutions for querying the NPDB :

§ ETSI Core INAP

§ ANSI IN Query

The following network operator option is defined for MO calls in VMSCA and for forwarded calls in the GMSC and VMSCB:

§ Originating call Query on Digit Analysis (OQoD).

The following network operator options are defined for the MT calls in the GMSC:

§ Terminating call Query on Digit Analysis (TQoD);

§ Query on HLR Release (QoHR).


2-2). Mobile Number Portability OV (GSM/UMTS) – SRF-based Solution

§ MNP-SRF supports for both Non-Call Related Signalling and Call Related Signalling MNP cases

§ SRF-based approach for Mobile NP architecture and call flow [refer to 3GPP 23.066]

§ When the MNP-SRF performs a database query, the number will be present depending on the routing modes.

§ In SCCP routing mode, the MNP-SRF relays the incoming message to another node (e.g. the HLR) and “manipulates” the SCCP routing addresses such, that the destination node responds back to the message originator.

§ In TC routing mode, the MNP-SRF responds to the incoming messages directly based upon information it receives from the destination node.

§ Indirect Routing Scenario: The messages are routed to number range holder network that performs then the MNP lookup in its database.

§ Direct Routing Scenario: With Direct Routing enabled, each provider directly sends messages to the recipient network

§ SCCP and TC routing options are available for both routing scenarios,


2-3). Support of Optimal Routing (SOR)

§ With the SOR feature, SRI messages having the SOR parameter is populated, international gateways can query the Number Range Holder network to verify ported status of a number before actually routing the call.

§ Without the SOR feature, international gateways would route the call to the gateway of the Number Range Holder network which is then responsible of further call routing.

§ The MNP-SRF supports the SOR feature.


2-4). Mapping between MAP and ISUP parameters

MAP Parameters

SRI Ack


ISUP Parameters

IAM

IMSI

Subscriber IMSI


CdPN

MSRN

MSRN

MSRN

MAPS TO

GAP

N/A

MSISDN

Not Present


FCI Bit M Indicator

1

MNP Indicator

Not Present




MAP Parameters

SRI Ack


ISUP Parameters

IAM

IMSI

Default IMSI


CdPN

Dialled DN

MSRN

Dialled DN

MAPS TO

GAP

N/A

MSISDN

Not Present


FCI Bit M Indicator

1

MNP Indicator

NotKnownToBePorted




MAP Parameters

SRI Ack


ISUP Parameters

IAM

IMSI

Default IMSI


CdPN

RN

MSRN

RN

MAPS TO

GAP

Dialled DN

MSISDN

Dialled DN


FCI Bit M Indicator

1

MNP Indicator

OwnNumberPortedOut





2-5). WNP Call Routing via IS-41

§ In ANSI-41, the switch launches a NPREQ query.

§ NPDB will respond with the LRN of the switch that is providing WNP service to the ported called party.

§ LRNs are at the heart of the call delivery process.

§ LRNs uniquely identify a specific switch in the North American wireline and wireless networks.

§ LRNs are used to route calls to ported numbers.

§ The Location Routing Number (LRN) Method of call delivery in a portability environment is used in North America (IS-41).

§ Historically, all numbering plans have assumed a fixed relationship between a customer’s number and a physical switch location.

§ In an LNP environment, physical switch location is decoupled from the customer’s number, the number becomes virtual.

§ The LRN is the link between the virtual number and the physical location.

§ In order to deliver calls, the LRN associated with the dialed number must be determined.

§ This is done by performing an LRN query.



3). NP in RFC Overview:

3-1). ENUM for Number Portability (RFC4769)

§ This Enumservice is used to facilitate the routing of telephone calls in those countries where number portability exists.

§ The purpose of this Enumservice is to provide routing information for telephone numbers

The following Enumservice is registered with this document:

§ "pstn" to indicate PSTN routing data, including number portability data, non-ported telephone number data (individually or in number blocks), and

§ other PSTN-oriented data that is associated with E.164 telephone numbers.

§ These URIs may contain number portability data (5 parameters) as specified in RFC 4694


3-2). Service Provider Number Portability Schemes (RFC 3482)

§ Refer to (1-4) item 1 to item 4


3-3). Five parameters in the "tel" Uniform Resource Identifier (URI) to carry the number portability (NP)-related information: (RFC 4694)

§ Includes rn, npdi, cic, rn-context and cic-context, by extending the "parameter" production rule of the "tel" URI defined in [RFC3966].

§ can be passed to the next-hop network node after an NP database dip has been performed.

§ use the NP-related information in a received "tel" URI to determine routing.


3-4). cic and cic-context parameters: (Carrier Identification Code)

§ The "cic" parameter carries the CIC information.

§ The "cic-context“ parameter describes how the "cic" parameter value should be interpreted when the value is not a "global-cic"

§ Carrier Identification Code (CIC) identifies the current freephone service provider for a freephone number. This parameter can also be used to carry the pre-subscribed or dialed long-distance carrier information.

§ For a "global-cic", the CIC information after "+" MUST begin with a valid E.164 country code.

§ For a "local-cic", the CIC value in the "cic" parameter MUST be interpreted according to the "cic-context".

§ For example, if the national CIC value is in the "cic" parameter, the "cic-context" MUST contain a valid E.164 country code after "+" if it is in the "global-hex-digits" format.

§ The inclusion of the visual separator in the "cic" is optional.


3-5). rn and rn-context parameters: (Routing Number)

§ The "rn" parameter carries the routing number information.

§ The "rn-context" parameter describes how the "rn" parameter value should be interpreted when the value is not a "global-rn"

§ A routing number can also be used to indicate the switch or network node that originates a call or service similar to the Jurisdiction Information Parameter in Signaling System Number 7 (SS7) Integrated Services Digital Network User Part (ISUP).

§ The first "hex-phonedigit" value in "local-rn" or "local-cic" MUST be a hex-decimal digit.

§ For a "global-rn", the routing number information after "+" MUST begin with a valid E.164 [E164] country code.

§ For a "local-rn", the routing number in the "rn" parameter MUST be interpreted according to the "rn-context".

§ For example, if a national routing number is in the "rn" parameter, the "rn-context“ MUST contain a valid E.164 country code after "+" if it is in the "global-hex-digits" format.

§ Hexadecimal digit is allowed in the "local-rn".

§ The inclusion of the visual separator in the "rn" is optional.


3-6). npdi parameter: (Number Portability Dip Indicator)

§ The "npdi" parameter carries such an indicator

§ NP database dip indicator is used to inform the downstream servers or switches during call setup that there is no need to perform the NP database dip for a geographical telephone number again.

§ The "npdi" parameter in the URI that indicates a NPDB query has already been done can also prevent routing loop.

§ If the "tel" URI contains the "npdi" parameter, the network node MUST NOT retrieve the NP-related information for geographical telephone numbers even if it is set to do so.

§ The network node MUST make the routing decision based on the CIC. The call is actually routed based on the CIC value in the "cic" parameter

§ The network node MUST NOT remove the "cic" parameter unless it is handing over the call to the carrier or service provider identified by the CIC and the local policies require it to remove the "cic" parameter.


3-7). Mapping NP-related parameters in a "tel" URI to the NP-related information in the ISUP message depends on the national ISUP implementation

§ For a non-ported geographical telephone number, the network node MUST convert the phone number in the ISUP Called Party Number parameter to a phone number

§ The network node MUST convert the phone number that is marked as the "ported number" in the ISUP Generic Address Parameter (GAP) to a phone number in either the "global-number" or "local-number" format [RFC3966]

§ The network node MUST include the "npdi" parameter in the "tel" URI that is used for routing when the Ported Number Translation Indicator (PNTI) bit in the Forward Call Indicator (FCI) parameter is set to "1".

§ The network node MUST include the "cic" parameter in the "tel" URI that is used for routing when the ISUP Carrier Identification Parameter (CIP) is present.

§ The network node MAY include the "rn" parameter in the "tel" URI associated with the caller information when the ISUP JIP is present.


4). NP in IMS Overview:

4-1). IMS Number Portability OV

Possible Solution Approach IMS NP:

§ IM-SSF NP in CSCF Domain: Using INAP/CAP to query existing NPDB

§ MGCF-based NP in MGCF Domain: Using MGCF/SGW to query NPDB

§ TSF-Based NP in CSCF Domain: : Using TSF (as an AS) to query NPDB (with SIP interface)

§ BGCF-based NP in CSCF Domain: Using BGCF to query NPDB (with SIP interface)

§ ENUM-Based NP: Using E.164 Number Mapping (ENUM) with updated information from NPDB

§ Note: The digit prefix (or string) needs to manage for NP solution, and control further routing control among different routing mechanism and call scenarios.


4-2). IMS NP: Solution OV

IM-SSF NP in IMS Domain: Using INAP/CAP to query existing NPDB (IN/SCP):

§ IM-SSF service bridges SIP and Customized Applications for Mobile Network Enhanced Logic (CAMEL) to allow for 800 services and Local Number Portability (LNP)

MGCF-based NP in MGCF Domain: Using MGCF/SGW to query existing NPDB (IN/SCP):

§ Based on provisioned with numbers/number blocks, MGCF/SGW can perform NP query to the existing NPDB (IN/SCP)

§ New RN in ported case will be used for further routing

§ Based on different routing mechanisms, some functions, like digit prefix removal, truncation, addition analysis or QoR cause value for SIP response code / reason header) may be required to enhance.

BGCF-based NP in CSCF Domain: Using BGCF to query NPDB (with SIP interface)

§ In one example the method may have the steps of:

§ Processing all calls with E.164 numbers in a BGCF (Breakout Gateway Control Function) or else

§ Executing digit analysis on a respective E.164 number in the BGCF

§ Querying by the BGCF: to retrieve a routing number from a NPDB (portable number database) if the respective E.164 number is ported.

TSF-Based NP in CSCF Domain: : Using TSF (as an AS) to query NPDB (with SIP interface)

§ Need to provision all the users for AS trigger

§ TSF may provide also telephone supplementary service features

§ AS returns the result of RN+DN (either INVITE or 3xx) where 3xx may not access other AS

§ AS supports SIP redirect mechanism to interwork with centralized NP DB with SIP interface (on existing NPDB)

ENUM-Based NP: Using E.164 Number Mapping (ENUM) with updated information from NPDB

§ ENUM allows service providers the ability to translate E.164 phone numbers into IP addresses (Destination Operator) for routing packets over IP networks.

§ Operator/Carrier ENUM is a private, secure DNS database service, it is accessible only by operators who register URIs.

§ Operator/Carrier ENUM offers complete market coverage from a single source, offering IP services access to number portability ported data from all Number Portability Administration Center (NPAC) regions.

§ Operator/Carrier ENUM provides an interworking function & interface to access and query the existing NPDB - synchronize between NP DB and ENUM

§ For global number resolution of international GSM destinations, the ENUM service transparently conducts SS7 queries to determine number ownership and returns the proper URI via ENUM, hiding the complexity of the SS7 queries from the IP-based service.

§ Carrier ENUM in IPX for Number Portability can be applied to GSM/UMTS operators (as transit node – like SIP proxy perform NP query).

§ Operator/Carrier ENUM Service enables operators’ switches to query the most recent (ported) routing information for a subscriber’s E.164 telephone number in a ported environment, allowing them to complete a call or message attempt to that subscriber.

§ The Operator/Carrier ENUM Service also determines how to route IP-based services to a number portability ported destination utilizing the routing mechanism assigned by an operator.

§ Populate URI with either rn and npdi as per RFC 4694 or with NP prefix


4-3). IMS NP Discussion: Routing Mechanism and Call Scenario (N/A TBD)


4-4). NP: Security and Operation Concerns (N/A TBD):


1 則留言:

  1. Thank you for sharing very useful information.

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