Dependable Voice in Today’s VoIP Networks

Voice over IP (VoIP) is transforming the world of telecommunications. As service providers transition from traditional circuit-switched network infrastructure to VoIP, they must address the challenges of delivering service flexibility and excellent voice quality, while continuing to meet high customer expectations.

The migration to VoIP presents a fundamental change in how voice networks are built, operated, and maintained. With a variety of consumers and enterprises accessing the network across a number of different network types (Cable, DSL, T1/E1, etc.), providers must solve the many voice and service quality and interoperability problems of the new VoIP network. The new VoIP devices, network types, and interconnectivity lead to problems such as:

NAT/firewall traversal
Security
Inter-carrier peering
Differing codec formats
Packet impairments (packet loss, delay, and jitter)
Voice impairments (echo, level mismatch, and noise)
Coding distortion (direct and/or tandem)

Fortunately, these issues are all resolvable at the IP network border with Ditech Communications’ VoIP Border Services solutions.

NAT/Firewall Traversal, Security, and Inter-Carrier Peering

The most common problem that service providers encounter when deploying hosted IP services is the inability of subscribers’ voice equipment to work seamlessly behind Network Address Translation (NAT) equipment and firewalls. Ditech’s Session Border Controllers (SBCs) work with near- and far-end equipment to ensure that subscribers can connect anywhere, anytime, without having to reconfigure their equipment. Ditech’s PeerPoint™ C100 even solves the NAT issue in a Microsoft® Live Communications Server (LCS) environment.

Ditech’s PeerPoint SBCs also protect the service provider’s back-end servers from security threats and hide the internal network topology information that would otherwise be exposed by application-layer signaling protocols such as SIP and MGCP. By providing border security with inter-carrier connectivity features, Ditech’s SBCs are the right solution for consistent, dependable, and flexible VoIP deployments.

Codec Transcoding

As VoIP becomes more widely deployed, carriers are challenged to support different types of VoIP media streams, including uncompressed and compressed codecs, as well as various payload sizes. A straightforward solution to issues such as codec normalization for the core network and bandwidth optimization for access facilities and leased lines is becoming apparent.

Ditech’s Codec Transcoding feature for the Packet Voice Processor provides support for any-to-any voice codec transcoding with a universal media transcoding framework and an industry-leading array of wireline and wireless codec formats. The advanced voice processing architecture of the PVP supports nearly 50,000 transcoding sessions per rack with very low transcoding delay.

Voice Quality in the Packet World

Ditech’s Voice and Packet Quality Assurance™ (VQA/PQA) technologies for the Packet Voice Processor enable carriers to significantly improve the total end-to-end voice quality of VoIP networks. VQA™ for Ditech’s packet products offers the same industry-leading technologies from Ditech’s TDM products, providing noise reduction, enhanced voice intelligibility, voice level control, and acoustic and hybrid echo cancellation. Ditech’s PQA™ features address voice quality issues specific to VoIP, such as packet loss, delay, and jitter, and reduce the effects of these impairments to dramatically improve overall call quality and clarity.

In addition, with Ditech's Voice Quality Management (VQM), voice and packet impairments are non-intrusively measured on every call, providing a comprehensive view of the speech quality in the VoIP network.

With Ditech’s VQA and PQA solutions deployed at the IP network border, service providers can centralize high-performance voice processing to enable a universal network approach to voice quality. By deploying the Packet Voice Processor at the service edge or IP peering point, service providers eliminate the need to support expensive and ineffective end-point devices.

Echo Cancellation and Voice Enhancement for VoIP-PSTN Gateways

As an alternative to Ditech’s packet network solution, Ditech’s VQA for VoIP-PSTN Gateways solution can be deployed on the PSTN side of a VoIP gateway. Ditech’s TDM-based VQA™ solution addresses key impairments to speech quality through an advanced set of algorithms to balance mismatched speech levels, remove background noise, cancel hybrid and acoustic echoes, and improve the fidelity of low bitrate VoIP calls through an Enhanced Voice Intelligibility feature that helps compensate for lost or attenuated speech formants.

For gateways with only hybrid echo issues, Ditech's Echo Cancellation for VoIP-PSTN Gateways solution leads the industry in performance with up to 192 ms tail delays. Ditech’s TDM solutions are available on carrier (T1, E1) and enterprise (DS-3, STS-1, OC-3, STM-1) platforms.