Local Number Portability (LNP)

Allows the 2020 IMG to route ported numbers for SIP and SS7. Routing on LNP is supported on ANSI protocol only. Mapping of LNP parameters is supported on both ANSI and ITU. The 2020 IMG complies with the following:

Generic Example

Below is call flow for a basic LNP scenario. Subscriber A (508-4445555) is calling Subscriber B (508-8623606). Subscriber B has been ported and the Local Exchange Carrier (LEC) servicing Customer B is  Local Exchange Carrier 2 (LEC2) and its Local Routing Number is (333-2233445)

CF_Local_Number_Portability.png

 

Note: The 2020 IMG does not perform the LNP.

 

TAGS

The LNP feature adds the following tags into the R-URI Header.

   
rn The routing number tag is used to convey the location routing number
npdi The number portability dip indicator tag indicates that an LNP query has been performed.

 

Examples

INVITE sip:3606;rn=2233445566;npdi=yes@10.129.43.23:5060 SIP/2.0
INVITE sip:3606;rn=2233445566;npdi@10.129.43.23:5060 SIP/2.0
INVITE sip:3606;npdi=yes@10.129.43.23:5060 SIP/2.0
INVITE sip:3606;npdi@10.129.43.23:5060 SIP/2.0

 

 

SIP to SS7 Interworking

The Local Number Portability feature interworks the SS7 LNP information into SIP network. Refer to call flow diagrams below.

SS7 to SIP Call Flow

CF_Local_Number_Portability_SS7_SIP.png

 

 

SIP to SS7 Call Flow

CF_Local_Number_Portability_SIP_SS7.png

 

SIP to SIP-I

Local Number Portability (LNP) allows a customer the ability to transfer either an existing fixed line or mobile telephone number assigned by a local carrier and reassign it to another carrier. The 2020 IMG now supports taking the LNP data in the R-URI on the SIP leg and interworking it into the R-URI and ISUP MIME on the SIP-I leg. The 2020 IMG also supports taking the R-URI message from the SIP-I leg and interworking it into the R-URI message on the SIP leg. This functionality is by default always enabled and does not need any special configuration for it to function.  

The LNP data in the IAM message is encapsulated in the GAP and FCI parameters. The GAP digits field carries the ported number (equivalent to RN tag). The FCI M-bit carries the ported number indication (equivalent to NPDI tags). For SIP-I, the LNP data in the R-URI and in the IAM are redundant. The 2020 IMG will retrieve the LNP data from the R-URI and the IAM message will not be parsed.

 

SIP-I to SIP scenario

SIP-I leg - The R-URI will be parsed to retrieve the LNP data (RN and NPDI tags).

SIP-I leg - The IAM in the ISUP MIME will not be parsed.

SIP leg - The LNP data will be relayed in the R-URI as RN and NPDI tags.

SIP to SIP-I scenario

SIP leg - The R-URI will be parsed to retrieve the LNP data (RN and NPDI tags).

SIP-I leg - The LNP data will be relayed in the outgoing SIP R-URI as RN and NPDI tags in the user-info part.

SIP-I leg - The LNP data will also be relayed in the outgoing IAM (ISUP MIME) as GAP and FCI parameters.

 

Note: The LNP data is relayed between SIP and SIP-I and no processing of the data will take place.

 

SIP - SIPI Call Flow

The Call Flow below represents the interworking of LNP from both SIP to SIP-I and SIP-I to SIP. The call flow displays a video call being received from MSC A in SIP-I format. The 2020 IMG will receive the call and will add the LRN and NPDI parameters into the INVITE message sent out on the SIP leg to the Video Gateway. The Call Flow below references the Call Trace that is linked in the Call Trace Example in next section.

 

CF_Local_Number_Portability_SIP_SIPI.png

 

Call Trace Example

Refer to the topic Call Trace LNP (SIP-SIPI) to display the call trace for the call flow diagram above.

 

Configuration

There is no configuration required. The LNP Handling of SIP to SIP-I feature by default is always enabled.

 

Additional Information (SIP-SIP-I)

Interworking Format
SIP to SIP-I (Inbound SIP INVITE)

INVITE sip:508111@10.129.45.104;rn=6664444;npdi=yes SIP/2.0\r\n

INVITE sip:508111;rn=6664444;npdi=yes@10.129.45.104; SIP/2.0\r\n

SIP to SIP-I (Outbound SIP-I INVITE) INVITE sip:508111;rn=6664444;npdi=yes@10.129.45.104; SIP/2.0\r\n
SIP-I to SIP (Inbound SIP- I INVITE)

INVITE sip:508111@10.129.45.104;rn=6664444;npdi=yes SIP/2.0\r\n

INVITE sip:508111;rn=6664444;npdi=yes@10.129.45.104; SIP/2.0\r\n

SIP-I to SIP (Outbound SIP INVITE) INVITE sip:508111;rn=6664444;npdi=yes@10.129.45.104; SIP/2.0\r\n
SIP to SS7 INVITE sip:508111;rn=6664444;npdi=yes@10.129.45.104; SIP/2.0\r\n
SS7 to SIP INVITE sip:508111;rn=6664444;npdi=yes@10.129.45.104; SIP/2.0\r\n