Carriers are
faced with several challenges when they try to interconnect with
other partners’ VoIP networks:
- The
need to support different makes of VoIP gateways and network
infrastructure.
- The
need to collect accurate call detail records for charge
settlements between originating and terminating partners.
- The
need to maintain anonymity of the partners exchanging
traffic, and
- The
need to protect the integrity of its own service infrastructure.
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The
current practice of using a TDM switch or a pair of media gateways
linked in a back-to-back configuration to convert voice from VoIP
to TDM and then back to VoIP is not cost-effective and the voice
quality suffers.
MediaRing VoizBridge, deployed at the edge of a carrier’s
network, enables centralized control of all VoIP traffic entering
and leaving the network. For VoIP-VoIP traffic, MediaRing Voizbridge
keeps the traffic in IP form throughout the call. It does this
by relaying the call signaling messages from the originating network
to the terminating networks, while maintaining call detail records
to support billing and settlement. This obviates the need for
expensive TDM ports or intermediary media gateways to support
transit VoIP traffic. The TDM ports that are freed up can be redeployed
for TDM-TDM traffic.
Owing to interoperability
issues between different makes of equipment, some carriers resort
to implementing independent network domains (e.g. Cisco-only,
Clarent-only) to serve different group of customers. No traffic
exchange is possible between these domains; the carrier’s
revenue potential is curbed while resources are not fully utilized.
MediaRing VoizBridge supports flexible internetworking between
devices having different variation/implementations of the H.323v2
VoIP protocol standard. MediaRing VoizBridge can serve as a voice
hub to aggregate traffic received from and sent to partner networks.
Likewise, for VoIP-TDM traffic, a pool of media gateways with
IP connection to MediaRing VoizBridge on one end and TDM connection
to the TDM switch on the other can be shared among multiple partners.
MediaRing
VoizBridge enables carriers to turn up new partners readily and
cost-effectively.
Security - Topology Hiding &
NAT Traversal
MediaRing VoizBridge hides the actual gateway IP addresses from
external partners. Instead of providing a long list of gateways
to a partner to be added on to their gateways’ access list,
the carrier now only has to pass on the IP address of MediaRing
VoizBridge. This eases management and administration; changes
in the carrier’s network (for instance, change of IP address
range, or add/removal of a particular gateway) can be kept transparent
from its partners. Topology hiding also helps protect the carrier’s
service infrastructure from DoS and other attacks.
Carriers and service providers deploying VoIP networks are recognizing
the need to protect the infrastructure from hackers and denial
of service (DoS) attacks. Providers establish peering relationships
by interconnecting their networks, either by collocating and connecting
via LAN or WAN networks. Interconnected networks become one larger
network, each side inheriting the strengths and weaknesses of
the other. The second issue for connectivity between carriers
- the VoIP traffic may need to traverse private and public address
spaces between the carriers’ IP domains. Service providers
targeting the VoIP Wholesale Peering market, whose traffic has
to cross the boundaries of different address spaces will find
that dynamic Network Address Translation (NAT) is a necessity.
This is applicable when connecting enterprise networks to carrier
backbones too.
MediaRing VoizBridge implements Network Address and Port Translation
(NAPT) for both media and signaling packets. The NAPT function
allows carriers to hide their network topology from suppliers
and partners. Carriers can also administer strict call control
over their networks using MediaRing VoizBridge’s device
access authentication and access lists. MediaRing VoizBridge’s
ability to provide VoIP security becomes very important when carriers
start to offer services to the enterprise and consumer markets.
H.323/SIP
Inter-working Function
The H.323/SIP Inter-working Function (IWF) is one of the key features
in the MediaRing VoizBridge solution. With H.323 still being one
of the dominant protocols in legacy infrastructure, and SIP quickly
gaining acceptance in service providers for its simplicity and
internet orientation, the IWF feature is a ‘must-have’
in an IP-IP peering solution. The H.323/SIP IWF works at the edge
of the H.323 and SIP networks, serving as an H.323 endpoint or
a SIP user agent. The protocol mediator converts an incoming H.323
call into a SIP call and then sends the call to a SIP user agent.
Conversely, incoming SIP calls are converted to H.323 calls and
sent to H.323 endpoints. Whether an H.323 call is converted to
SIP, or a SIP call is converted to H.323, the transition happens
seamlessly as viewed by the components involved in the call.
Call Session Routing
MediaRing VoizBridge can connect to either a 3rd party Open Settlement
Protocol (OSP) Server, Gatekeeper, SIP Proxy or to an internal
routing engine - MediaRing
Route Management System, component for route determinations,
depending on the network implementation. MediaRing’s Route
Management System (RMS) compliments the VoizBridge solution to
provide centralized provisioning and management of routing decisions.
The RMS allows carriers to optimize call routing to meet business
needs by enabling advanced, flexible routing logic via a simple,
web-based graphical user interface (GUI)
