Number Portability Impacts on

1

• Number Portability Impacts on
• IP Telecoms Interworking
• James Yu
• NeuStar, Inc.

2
Number Portability

• Number portability (NP) allows the telephone
  subscribers to keep their phone numbers when they
  change the
• Service provider Service Provider Portability
• Location Location Portability
• Subscribed services Service Portability

3
Service Provider Portability

• Supported in many countries
• Adopted schemes vary
• All Call Query
• Query on Release
• Dropback
• Onward Routing
• Some involve centralized databases, others do
  not.

4
Service Provider Portability Schemes
Centralized
Centralized
Number Porting
Number Porting
New SP
New SP
1
3
4
2
Old SP
Old SP
Orig.
Orig.
2 release w/o
Donor SP
1
All Call Query
Query on Release
Number Porting
Number Porting
New SP
New SP
4
Old SP
Old SP
3
Orig.
Orig.
3 release w/t
Donor SP
Donor SP
1
1
2
2
External or integrated
External or integrated
Dropback
Onward Routing
5
Network Routing

• North America
• Location Routing Number (LRN) in the ISUP Called
  Party Number (CdPN) Parameter for routing
• Called directory number (DN) carried in Generic
  Address Parameter
• Translated Called Number Indicator (TCNI) in the
  ISUP Forward Call Indicator (FCI) Parameter set
  to indicate that database dip has been performed
• Europe
• Routing prefix added to the called DN in the ISUP
  CdPN Parameter
• Proposed ISUP enhancements for NP (Q.769.1)
• Adding routing prefix to the Called DN and use
  Nature of Address (NOA) field to indicate that or
  two separate parameters (one is new) one carries
  the routing number and the other carries the
  called DN. NOA used if the routing number is
  carried in the ISUP CdPN parameter
• Number Portability Forward Information (network
  option) to indicate whether NP query is done or
  not and whether the DN is ported nor not

6
Database Query

• North America
• AIN (ANSI SS7 MTP/SCCP/TACP)
• IN (ANSI SS7 MTP/SCCP/TACP)
• ANSI IS-41 (ANSI SS7 MTP/SCCP/TACP)
• GSM (PCS 1900) MAP (ANSI SS7 MTP/SCCP, ITU-TS
  TCAP)
• Europe
• INAP CS1 (ITU-TS SS7 MTP/SCCP/TACP)
• INAP CS2 (ITU-TS SS7 MTP/SCCP/TACP)

7
IP Telecoms Interworking
GWd1
New SW
Internet
GWo
Number Porting
Call orig. from SCN
GWd2
Old SW
SIPd1 /GKd1
SIPo /GKo
SIPd2 /GKd2
Re-Association
GK - Gatekeeper GW - Gateway NP - Number
Portability SCN - Switched Circuit Network SIP -
Session Initiation Protocol SW - Switch o -
Origination d - Destination
8
Issues

• Where to query for NP information
• At Originating GW/SIP Server/GK
• Too many national variations to deal with -gt need
  a common approach
• At Destination GW/SIP Server/GK
• Too late, may be the wrong GW/SIP server/GK not
  all the GWs/SIP servers/GKs can reach all the
  destination E.164 numbers
• Another entity within Internet
• Additional delay
• Inefficiency if it also handles user data (e.g.,
  voice/data packets)
• The entity that retrieves the NP information may
  need to wait and collect all the address
  information before retrieving the NP information
  if overlap signaling is encountered.

9
Issues (Continued)

• How to query for NP information
• SS7/TCAP over IP (many national variations)
• A new and common scheme
• Need to standardize the scheme
• Need to retrieve the routing information (e.g.,
  LRN or routing prefix) if an existing scheme
  (e.g., DNS) is enhanced
• NP information, if retrieved, needs to be carried
  over internet in a common format that can be
  converted to national ISUP at the destination GW
• ISUP/SS7 over IP (e.g., between two GWs)
• Encapsulated ISUP in SIP
• SIP protocol
• H.225.0

10
Conclusions

• Number portability can occur in the SCNs and
  within Internet
• Many issues are related to number portability and
  need to be addressed altogether
• Develop efficient schemes
• Use standardize ITU-TS and IETF protocols
• Address all aspects of number portability (e.g.,
  not just service provider portability)