VoIP and Number Portability: Perceived v. Real Problems Tom Kershaw Vice President, VoIP VeriSign

2 Agenda Background Circuit Switched Number Portability Addressing and Portability on the Internet Addressing and Portability for Wireless Data A Parallel: H.323 and SIP Key Portability Issues Today Portability Architectures for VoIP Portability Architectures for MMS Recommendations, Bold Statements, Misc. Controversy

3 Portability and the PSTN Portability is based on regulatory mandate – Communications Act of 1996 Technical Approach is based on PSTN concepts such as: Rate centers LATAs Lines Hence, the LRN Mobile has followed this model in portability and roaming, which uses TLDNs in much the same way as LRNs LRNs do little more than tell the network what trunk group to use to get to the subscriber What if you dont have trunk groups, rate centers and geography?

4 Portability and the Internet Internet addressing introduces clear separation between Name Space and Address Users are identified by URLs and Domain Names Hence, the DNS constellations that provides root addressing for the Internet: Tree-based Highly resilient Segmented Address Structures: tomkershaw verisign Address space controlled and administered by the name owner – you can have any unique address within this domain Address space administered by Registrars; any unique address can be registered within each TLD Administered by the industry/go- vernment

5 Portability and the Internet Namespace on the Internet maps to a network address ie to Names are segmented: If I want to change my name – I have three Change the TLD ie assuming it is Change the domain to a new owner/name ie I can port my namespace into a new domain, assuming its available in that domain, but tomkershaw is not globally unique. Address space is assumed to be infinite. Names are fully geographic, Addresses Change Dynamically

6 Service Application Portability and ENUM DNS e164.arpa page: Pager HTTP tel: TEL SMTP SIP Service AddressProtocol To port this number, I can map the LRN to a SIP URI/:mailto:, or… Set of NAPTR RRs Change the domain space in the routing record….. ENUM uses DNS to resolve internet namespaces for VoIP

7 The Fork in the Road PSTN VoIP Path 1: Adapt current PSTN system to IP Path 2: Create an Entire New System Optimized for IP

8 The Fork in the Road PSTN VoIP H.323 SIP Quickest path to market Non- Disruptive Phased Migration Expensive Difficult to Integrate with IP Voice is special…. Slower to market Built to last – not a corner cutter Lacks features of original for some time Wins in the End

Portability Scenarios for VoIP

10 Scenarios for Number Portability 1) PSTN to PSTN (we have this sorted out) 2) PSTN to IP 3) IP to PSTN 4) IP to IP 5) MMS to MMS (MMSC to Handset) Bold Statement #1: Scenario 2 is the most important issue for VoIP operators today Bold Statement #2: Scenario #5 is the most important issue for mobile operators today Dont Mix the Two Up

11 Exec Summary (the Punch Line) Currently, the biggest issue for VoIP Portability is introducing geographic portability All other issues are minor in comparison This must be addressed by the industry for VoIP to take off Lack of geographic portability seriously hampers voip and also means most voip operators will not support portability at all Until this is solved, other discussions are moot The NPAC should be used for calls to or from the PSTN IP addressing mechanisms such as ENUM and private trees should be used for IP to IP I and P are the two most important letters in VoIP Number portability should be implemented as a change to a resource record in ENUM/Location Server

12 Key Points Current industry discussions on Implementing Portability for VoIP have nothing to do with VoIP VoIP operators did not ask for this VoIP operators dont benefit VoIP operators need geographic portability, not URIs in the NPAC The Real driver for these initiatives is MMS When an MMS is received by an originating MMSC, it needs to find the terminating MMSC In non-ported case, number is mapped to a carrier (easy) In ported case, the LRN needs to map to a mailto: address This is a very REAL problem that needs to be solved

13 Geography and VoIP VoIP separates the access network from the address Access network can physically be anywhere; if you are on the network you are addressable Similar structure to mobile – needs to have similar functionality With recent FCC rulings, structure of telephone addressing will change Rate Centers, City Codes, and NPAs will cease to be relevant City Codes already losing relevance DIDs will be available on demand, from anywhere, to anyone Potential for anarchy…… …..but thats how the Internet works

14 My Address in VoIP Home (VA) Cable modem My Phone Numbers: Friend (Dallas) Office (Mt. View) Family (Detroit) Local (VA) My Service Provider (Hawaii) IP Network My URIs

15 The Geographic Portability Problem 1) Subscriber living in Washington DC ( ) ports her number to IPCarrier; also buys a second line with phone number 415 because her son has moved to San Francisco 2) Calls from PSTN to are local under tarifing rules 3) Subscriber moves across the river to Virginia; changes DSL provider but keeps VoIP provider and same phone numbers 4) Subscriber is offered better deal by a mobile operator that combines fixed and mobile into one package 5) Subscriber: Cant port original number to new operator unless it has IMTs in the same rate center as xxxx Can only port 408 number to a new carrier she does not even know

16 Portability and VoIP to VoIP When there are 10 million VoIP lines in North America, ¼% (.0025) of calls will be VoIP to VoIP One of the big concerns of VoIP operators is reducing network round trips Most peering architectures will map a phone number to: A URI An IP Address (typically of a proxy or border element) The IP query will take place before a call is sent to the PSTN The IP query may call out to an LNP resource or the owner of the number will be up-to-date without querying the NPAC data If a number is VoIP to VoIP, why call out to two databases when you can do portability and addressing in one?

17 Simple Peering Architecture PSTN Media Gateway CallAgent Directory SIP/ENUM Service Broker Inter-Carrier Settlement (??) Subscriber Portal ASP Domain Applications/Services Operator A CallAgent CMTS CallAgent DSLAM Enterprise B IP Core Border Element Border Element

18 An IP-to-IP Addressing Flow SIP Redirect Engine ENUM/DNS Interface to CCE External Callouts (SIP or ENUM) Number Analysis and Normalization (e.164 or URL) TN Discovery TN Exists? Yes= BE RouteList External Callout Engine *LNP *CNAM *Carrier Select (ENUM or SIP) Route Engine TN To BE Route List Proportional Route Splay Route ToD/DoW Engine Class 4 Route Default (Trunk Group, PSTN Ctvty) Route Propagation: TGREP/TRIP/Manual Provisioning Port the number here Or call out to an external directory

19 Addressing in VoIP: The Internet Way Tier 1 ENUM Or Private Peering Misc. IP Network Location Server/Registrar Tier 2 ENUM Call Control IN NAPTR "u" "E2U+sip" Ported to IN NAPTR "u" E2U+mailto"

20 Porting in an ENUM Environment ENUMDNS Portability Request RRP | EPP Domain changed; Number ported DNS/ENUM Resolver Interface page: Page tel: TEL m SMTP Service Address (NAPTR RRs) Protocol fax: Fax In: e164.arpa Out: NAPTR RRs ENUM is a standard translation mechanism defined by the IETF that uses DNS to convert an E.164 telephone number into a set of addresses.

21 Extending the Model: Whois for VoIP (IRIS) DNS Option 1 Location Server/Registrar Tier 2 ENUM Call Control IN NAPTR "u" "E2U+sip" IN NAPTR "u" E2U+mailto" Device Resources WhoIs? Option 2Option 3 Perimeter Security and Interop Resources

22 Models for MMS Mobile operators have a different problem: Since endpoints do not have IP addresses, they will be ported with LRNs When a discovery takes place, they want a mapping of the phone number or LRN to a mailto: address Mailto address will correspond to an MMSC in the destination network Using this method eliminates the overhead of using the SS7 network and makes delivery more efficient Requires an up-to-date mail to address database This problem space is small (100 mobile operators x 3000 LRNs x 2 mailtos Private no/low cost solutions already out there for this

23 Conclusions Biggest portability issue for VoIP carriers is geographic portability This will become an increasingly focal issue VoIP operators do not benefit from extending LNP infrastructure to URIs or IP addresses in the immediate term Requiring a second dip to an external directory does not make sense – support E.164 portability directly on the IP network Mobile operators do have a strong need for an LRN to mailto solution – and there are solutions out there We must be very careful in our architectural decisions – the impacts are far reaching and in some cases we are solving problems before they manifest themselves In VoIP, E.164 is a NameSpace, not an Address – need to treat it accordingly

Thank You!