“VoIP Peering” is quite a general term that can be construed to mean any one of several models operating on different levels. The best known models involve carriers exchanging network connections, while others assist the enterprise in federating data and voice with partners, suppliers and customers – one can easily confuse Session Initiation Protocol (News
) (SIP)-trunking with carrier VoIP Peering.
For example, Broadvox’ (News
) GO! SIP Trunking solution gives enterprise and SMB customers the same savings and features that they would get by purchasing an IP or hybrid PBX. Broadvox employs Switch and Data’s PAIX VoIP solution to exchange its traffic with other providers in a facility via an all-IP peering environment, partitioned from other PAIX peering traffic to provide high voice quality service.
Robby Benedyk, product marketing manager at Tekelec (News
), explains: “Direct Peering is the first of three methods that can connect one operator with another. The user benefits from seamless services offerings and extends services beyond the operator’s own subscribers. Large operators benefit first, especially when they offer common service, and the relationship is well defined and controlled. This option may be too expensive for smaller operators due to interoperability testing costs.”
“Smaller operators can choose a Hub method, where a third party manages the interconnections,” says Benedyk. “This enables many smaller operators to connect with each other by placing the interoperability burden on the Hub provider. The Hub would host the central subscriber database, possibly using ENUM (Telephone Number Mapping), to provide routing. The Hub may also offer SIP normalization to manage protocol variations in the network equipment. This option put the Hub in control of access points, interconnection routing and security.”
“One step beyond a Hub is a more regulated model called a Federation,” says Benedyk. “This is a closed group that has agreed on a standard set of protocols, common goals, interoperability and security. The members benefit from the common testing and a well-defined set of behaviors within the group that reduce operational expenses and time to market. Provisioning and routing are defined by the group, tested by the group and managed by the group.”
Benedyk elaborates: “All three models include four vital elements: One, bi-lateral agreements; two, exposed access points; three, common provisioning mechanism; and four, shared applications. Finding the right model is based on weighing these options against a non-peering solution that improves operational and capital expenses.”
“The gradual adoption of some new service that is bearable in a VoIP-PSTN-VoIP network but can excel in a pure-IP peering solution will accelerate peering,” says Benedyk. “Killer apps fail where simple improvements shine. Unlimited subscriber plans show that having enough network bandwidth can open up use of new phones, data networks and additional services. Gradual advances of the VoIP network will lead to newer needs for the VoIP network.”
“The initial peering involved use of the PSTN because that was all that was available,” says Benedyk. “There were no ‘pure-IP calls’ because the only method to connect two operators was through the PSTN. The agreements on common provisioning and definition of the access points and routing have begun to open up the peering option. Operational costs still drive the timeline and rollout schedule in light of the current economic conditions. Strictly speaking, the notion of the PSTN in the loop fails to deliver advanced IP services (e.g. beyond voice). The definition of peering that once involved the PSTN has evolved as IP endpoints, hubs, federations and quality have matured to the point of being a normal part of the infrastructure instead of a new feature.”
Benedyk points out that many deals between carriers involve bilateral VoIP connections. An increasing number are adopting multilateral VoIP peering, which models the exchange of voice traffic as a free exchange, and which involves a different routing/lookup functionality such as ENUM or SRV.
Benedyk’s company, Tekelec, is a major telecom equipment vendor that develops equipment for peering environments. Tekelec entered the ENUM space from a market-leading position in SS7 systems with nearly 40 percent of global market share and high-capacity LNP databases. Tekelec’s solutions are deployed in eight of the 10 largest wireless carriers and six of the 10 largest wire-line carriers.
Take for example Tekelec’s EAGLE XG ENUM Server, a high-capacity, portability-corrected database that consolidates both VoIP and E.164 address information in a single network element to facilitate efficient service routing. It converts a ported or non-ported Telephone Number (TN) into a domain name, which is used to retrieve the Uniform Resource Identifier (URI) of the carrier or network device associated with that number. Service providers can deploy a hybrid operator/private Tier 1 ENUM solution to route VoIP calls, Short Message Service (SMS), Multimedia Message Service (MMS) and future multimedia services within their own network and across other operators’ networks. The EAGLE XG ENUM Server is designed to help alleviate peering problems for all types of operators including wireless, wireline, cable and non-facilities-based, and seamlessly routes and terminates calls between IP and circuit-switched domains that use different numbering schemes.
SBCs and Gateways
Because the world consists of a “network of networks”, getting packets to traverse network borders (not to mention firewalls and other security measures) can be a big problem. As it happens, AudioCodes offers their nCite line of Session Border Controllers (SBCs) to control media and signaling exchange across the network operator boundaries. Controlling the media “pinhole” establishes the foundation for policing, dynamic Network Address Port Translation (NAPT) and firewall traversal, admission control and bandwidth management as well as other inter-working functions. Signaling protocols are equally validated allowing QoS fields to be re-marked when passing between networks. It also generates Session Detail Records (SDRs) enabling the operator to control and manage its SLA with its customers as well as with other operators.
AudioCodes also offers their family of Mediant Gateways to enhance SBC capabilities by providing media transcoding where peering networks are supporting disparate codec sets. SBC and media transcoding capabilities are independently scalable.
VoIP Peering Checks In
Metcalfe’s Law states that the value of a telecommunications network is proportional to the square of the number of connected users of the system. Since the world’s networks aren’t a nice, distributed mesh owned by a single provider, all networks must be interconnected to each other to increase their respective utility, so all service provider network routes must converge on a type of physical layer 1 real estate called “hubs”, “carrier hotels”, “meet me rooms” and “collocation facilities”.
One major player, Telx, provides its own peering services at its facilities in both Phoenix, Ariz. and Atlanta, Ga. Telx also enables access to peering services provided by its customers. Voice and VoIP peering services are available within the Telx facilities across America.
There are various commercial (for profit) and independent (no-to-low cost) data and voice/VoIP peering exchanges, such as The Big Apple Peering Exchange (BIG APE) at 60 Hudson Street in New York; the Equinix GigE Exchange at 111 Eight Avenue, New York (linked to Equinix’s Newark GigE Exchange); the New York International Internet Exchange (NYIIX) – Telehouse, at 60 Hudson Street and 111 Eighth Avenue, New York; Palo Alto Internet Exchange (PAIX) Services, now operated by Switch and Data (SDXC), founded in 1996 as the first major carrier-neutral Internet exchange point, providing connectivity from multiple fiber providers at 60 Hudson Street and 111 Eighth Avenue, New York as well as 56 Marietta Street, Atlanta, Ga.; the San Francisco Internet Exchange (SFIX) at 200 Paul Street; and the famous Voice Peering Fabric (VPF) built in NYC by Stealth Communications (News
), a distributed private Ethernet network that functions as a meet-point for service providers and enterprises, located at 60 Hudson Street (NYC) / 56 Marietta Street (Atlanta) / 350 E. Cermak Road (Chicago) / 2323 Bryan Street (Dallas).
XConnect, founded by Eli Katz in 2005, is another major provider of federation-based peering and interconnection services dedicated to connecting telecom operators to enable multi-media end-to-end IP communications.
Perhaps the largest neutral peering provider for IP-enabled carriers and service providers, XConnect’s solutions encompass protocol interoperability, ENUM directory services, SIP-based peering, interconnect, registry services, security and policy management. XConnect was selected by the cable industry in the Netherlands to operate the world’s first nation-wide VoIP peering solution, and acquired the European carrier ENUM exchange e164.info and U.S.-based peering provider IPEERX in 2006.
Expect to see more use of managed ENUM registries, thus enabling call completion of outbound off-network calls as sessions to other federation members, with the rest routed to mobile and fixed-line networks. Multilateral peering relationships will begin to overtake older bilateral agreements. Carriers will enjoy increased flexibility in the multi-protocol, multi-vendor VoIP interconnection infrastructure – even now they’re able to choose peering and commercial policies ranging from settlement-free, pay by call, or pay-by-the-minute models.
Richard Grigonis is Executive Editor of TMC (News - Alert)�s IP Communications Group. To read more of Richard’s articles, please visit his columnist page.
Edited by Patrick Barnard