Mobile Number Portability (MNP)

Mobile Number Portability (MNP):

Mobile Number Portability (MNP) is the ability for a UMTS or GSM mobile subscriber to change the subscription network within a portability domain while retaining her original MSISDN.

Fig 1: General Architecture of Portability for Calls 

Few Definitions to understand the MNP feature: 

Number Range Holder Network (NRHN): The Network to which number range containing the ported number has been allocated. 

For Example if a number which is in process of porting is belongs to Vodafone network, then the Vodafone treated as Number Range Holder Network (NRHN). 

Donor Network: A subscription network from which a number is ported-out in porting process. This may or may not be the Number range holder network. 

For example if a subscriber is ported-out from Vodafone to Airtel, then Vodafone  network if called as Donor network. If this number range belongs to Vodafone then it also called NRHN so in this NRHN and Donor network would be same i.e. Vodafone. but if this number is already ported in to Vodafone from Idea and again it is ported out to Airtel, then the Vodafone network is called as only Donor network and Idea would be NRHN.

Number Portability Database (NPDB): A Database which provides portability information like Number is ported out or not  (portability Status) and if ported out then provides the Routeing number (RN).

Routeing Number (RN): A Routeing number route the call to recipient network or subscription network. This is provided by NPDB or MNP-SRF.

Number Portability Status:  Information indicating the status of portability for Mobile subscriber. Portability can be:

- Own Number Ported Out

- Own Number not ported out

- Foreign number ported in

- Foreign number ported out to foreign network.

- Foreign number not know to ported 

Originating Network: Network where the calling party located.

Subscription Network or Recipient Network: An recipient network for the Mobile subscriber in porting process. 

For Example if a number which is in process of porting is belongs to Vodafone network and ported out to Airtel, then Airtel  

would be Recipient Network in this case.

Following routing methods are mentioned: these are the method implemented in portability domain based on the operator agreements.

- Direct Routing: Direct Routing of calls is PLMN options that allows to route calls directly from the PLMNs supporting this option to the ported subscriber's subscription network. 

For example: In the Fig 1, if a message(7) is originated inside the portability domain, in a PLMN supports the direct routing, this IAM (7) directly routed to the subscription network.   

- Indirect Routing: Indirect Routeing of calls is a PLMN option which allows to route calls from the PLMN supporting this option  via the number range holder network to the ported subscriber’s subscription network. 

For example In Fig 1, If a message(2) originated inside the portability domain, in a PLMN support indirect routing routes this IAM(2) to Number Range holder network. The Number range holder network route the calls to subscription network.

- If a call originated outside the Portability domain, then the IAM(1) routes to NRHN and then NRHN routes message(1) to Subscription network.

What changes needed to perform the portability:

case 1: if the number range holder network is identical with the donor network (Example if number is of Airtel and ported to Vodafone):

                           Airtel(NRHN, Donor N/W)             Vodafone (Recipient N/w)                 Idea ( Other N/w, Direct Routing)

                    ================================================================================

HLR                      REMOVE                                         ADD            

NPDB                 rn=ADD to voda                               ADD                                                                   ADD for vodafone

case 2: if the number range holder network is identical with the recipient network:(Example if number is of Airtel and ported in to airtel from vodafone) – Normal call.

                      Airtel(NRHN, receipint)             Vodafone (DONOR N/w)                 Idea ( Other N/w, Direct Routing)

                     ================================================================================

HLR                       ADD                                              REMOVE

NPDB                     rn=remove                                 remove                                         remove

Case 3:  if the number range holder network is different from both the recipient and the donor network: (Example if number is of Airtel and ported in to idea from vodafone)

               Airtel (NRHN)            Vodafone(Donor N/W)                   Idea (Recipient N/w)               BSNL( Direct Routing)

                 =================================================================================

HLR                                                                  delete                                add

NPDB         rn=update                                  delete                               add                                      update