Integrating Existing Number Portability Solutions in Carrier-ENUM Douglas Ranalli, NetNumber, Inc.

1. Integrating Existing Number Portability Solutions in Carrier-ENUMDouglas Ranalli, NetNumber, Inc. 12 January 2006 CDG Conference Call

2. About NetNumber • Provider of next generation addressing solutions to carriers and operators based on the NetNumber TITAN platform. • Transactional IP-Telephony Addressing & Numbering (TITAN) • Common transaction platform in operator’s network for both SS7/C7 and IP Addressing: • Number-Portability, Flexible-Numbering (GTT), etc: • Multiple protocols: • AIN 0.2, PCS-1900, GSM/MAP, IS-41, INAP, DNS, SIP and ENUM. • Multiple interfaces: • T1/E1 low-speed link, SIGTRAN and IP. • Carrier-ENUM: Flexible implementation options for the discovery of carrier-controlled IP-services. • ENUM query: • Different address resolution models can be configured on a country-by-country basis. • Up to 43,000 transactions/second on a single TITAN Edge server. • SIP Invite with 302 redirect: • SIP Invite to a TEL URI results in a SIP 302 “temporarily moved” response with one or more SIP URIs as contact addresses. • Up to 15,000 transactions/second on a single TITAN Edge server.

3. Customer/Partner Examples

4. Carrier-ENUM Background • Private service discovery infrastructure. • Accessed by all types of carriers. • Common domain name: “e164enum.net” • Standard query/response protocol as defined by RFC 3761. • Supports number-portability. • Focus of this presentation: • Carrier-ENUM implementation models that leverage existing number-portability solutions.

5. IMS ENUM Call-Flow Example • End-user dials E.164 to initiate service. • S-CSCF issues ENUM service discovery query to on-site or hosted ENUM server for a SIP-URI. • S-CSCF resolves host name within SIP URI using on-site or hosted private DNS infrastructure. • S-CSCF sends SIP Invite to destination I-CSCF. • I-CSCF queries HSS to get address of S-CSCF. • I-CSCF proxies Invite to destination S-CSCF. • Standard SIP/SDP session negotiation follows.

6. ENUM Implementation Options • DNS Delegation • ENUM service discovery via DNS delegation through Tier-0, Tier-1, Tier-2 infrastructure. • Central Portability Database • Central portability database fulfills role of Tier-0 and Tier-1 for a given country. • Solution utilized by GSM, CDMA and GRX/CRX interconnect providers in North America today. • Number-Block Assignment • Existing number-block assignment data fulfills the role of Tier-0 and Tier-1 for any non-ported network. • Simple extension of model being used in North America today. • IMSI Query • MAP query for IMSI address fulfills the role of Tier-0 and Tier-1 for any carrier/operator that supports IMSI addressing. • Solution being used by GSM operators in Europe today to interconnect MMS.

7. DNS Delegation • S-CSCF issues ENUM service discovery query to on-site or hosted ENUM server for a SIP-URI. • ENUM Server queries Tier-0 to identify a country-specific Tier-1 then queries the Tier-1 to identify the destination operator (NS record of operator’s Tier-2 name server). • ENUM server queries the destination Tier-2 nameserver to get a NAPTR record identifying an appropriate network entry-point (I-CSCF address) in the form of a SIP URI.

8. Central Portability Database • S-CSCF issues ENUM service discovery query to on-site or hosted ENUM server for a SIP-URI. • ENUM Server checks for locally provisioned portability data to identify the destination operator then checks for locally provisioned interconnect data to discover an appropriate I-CSCF address (or NS record) for the destination operator. • Key Benefits: • Resolution is extremely fast. No Tier-1 or Tier-2 wide area network queries required. • Originating operator can locally provision an appropriate interconnect address for a destination partner.

9. Number-Block Assignment • S-CSCF issues ENUM service discovery query to on-site or hosted ENUM server for a SIP-URI. • ENUM Server checks for locally provisioned number-block assignment data to identify the destination operator then checks for locally provisioned interconnect data to discover an appropriate I-CSCF address (or NS record) for the destination operator. • Key Benefits: • Resolution is extremely fast. No Tier-1 or Tier-2 wide area network queries required. • Originating operator can locally provision an appropriate interconnect address for a destination partner.

10. IMSI Query • S-CSCF issues ENUM service discovery query to on-site or hosted ENUM server for a SIP-URI. • ENUM server issues MAP query for an IMSI address to identify the destination operator then checks for a locally provisioned I-CSCF address (or NS record) for the destination operator. • Key Benefits: • Leverages existing operator investment in IMSI addressing to fulfill Tier-0 and Tier-1 function. • Originating operator can locally provision an appropriate interconnect address for a destination partner. • Solution already being used to interconnect MMS services today.

11. Recommendation • Document multiple options for integrating existing number-portability solutions in Carrier-ENUM. • Operators and GRX/CRX/IPX providers will benefit from flexibility. • Various Carrier-ENUM implementations work equally well in on-site or hosted ENUM server deployments. • Different solutions can be applied to different country-codes. • Solutions can be enhanced by use of third-party interconnect registries. • Multiple interconnect registries available today or under development. • Interconnect registries facilitate the exchange of appropriate interconnect data (points of interconnect) between carriers/operators. • Eliminate requirement for manual entry of interconnect data. • More sophisticated than wide-area-network query to a Tier-2 nameserver. • Different interconnect addresses for different partners.