By Ray Adensamer
Every day, contact centers connect with customers to deliver services across the globe. Advancements in telecommunication capabilities have allowed contact center operators to improve quality of service and expand their communication methods. Today, voice over internet protocol (VoIP) is fueling a new round of innovation in contact center features and capabilities.
VoIP offers a number of benefits for contact centers. As opposed to traditional circuit-switched communications, next-generation VoIP contact centers allow providers to deliver services across multiple modes of communication: voice, fax, email, instant messaging, Web, images, and video. Providers can take advantage of the open computing architecture to realize reduced costs and improved flexibility. VoIP long-distance backhauls are more cost-effective, making remote contact centers more financially viable. Finally, the standards-based interface delivers a robust ecosystem of best-in-class solutions.
However, there are common audio quality problems associated with VoIP telecommunication services in IP packet networks, including noise, packet loss, and echo. These problems pose significant challenges for adopters and diminish providers’ confidence in the conversion from circuit-switch to VoIP networks. To approach these service barriers, voice quality enhancement (VQE) software is required.
Tackling the Challenges of VoIP Voice Quality: Recent software advancements are allowing contact center providers to achieve the same audio quality on VoIP networks as on traditional circuit-switched networks. VQE software incorporates a variety of functions designed to tackle the audio challenges inherent in VoIP networks. One highly effective approach for addressing these challenges is to integrate VQE capabilities into an IP media server. An IP media server is a common, shared IP media processing resource used for a broad range of IP applications. Because an IP media server is a centrally deployed resource in the core of the network and is involved in real-time IP packet processing, it is the ideal technology and network location for addressing common sources of poor audio quality. Using this integrated approach creates a single network element that performs both IP-packet processing and voice quality enhancement. As a software solution, VQE does not require an additional network element; this reduces both capital and operational expenditures, providing benefits at one-fifth the cost of comparable hardware solutions.
Audio Noise: The freedom granted by mobile phones and the Internet means that people are now making calls from just about everywhere. Calls are no longer made from quiet offices, and background noise – from barking dogs to blaring traffic – drastically lessens call quality. Lower-quality devices such as cheap earpieces can further exacerbate the matter.
VQE software can address and solve the primary audio quality challenges facing today’s contact centers. For excessive noise, VQE offers three approaches:
- Noise Gating: This is a simple yet effective mechanism that reduces background noise. When no speech is detected, the signal is attenuated to prevent any unnecessary noise from being inserted. Providers can configure how much they want to decrease amplification to avoid making the line unnaturally quiet.
- Noisy Line Detection: Noisy line detection actively looks for and distinguishes four noise conditions: background noise, impulsive noise, continuous signal noise, and low signal-to-noise ratio. These conditions are reported to the application server, at which point the moderator can then choose to mute the noisy line or leave it unchanged.
- Noise Reduction: This service goes a step beyond noise gating, using digital processing techniques to remove unwanted noise while leaving the important speech signal intact. Because this process requires a great deal of processing power, noisy lines are dynamically identified and ranked before noise reduction is selectively applied.
Packet Loss: While the Internet is incredible on many levels, it isn’t perfect. IP protocols do not guarantee packet delivery; they can get lost or delayed when the networks get busy or congested. To solve the problem of lost packets, VQE software includes packet loss concealment. When packets are lost or unacceptably delayed in the IP network, the software replaces them with predictions from previously received audio. Unlike voice repair technology, which would have difficulty recovering from extreme packet loss in abnormal conditions, this process is designed to perform intelligent restoration of lost or delayed packets for a majority of congested network scenarios. By inserting estimates based on previously received packets, the software creates a speech rendering that closely resembles the original and reduces the occurrences of choppy audio.
Acoustic Echo: Similar to yelling in a cave, improper echo isolation can result in a caller hearing a delayed echo of their own voice. This happens when a speaker’s voice is transmitted back by the receiver’s microphone. Because the echo is often heard by all but the guilty party, it can be difficult to pinpoint the cause.
Acoustic echo cancellation (AEC) is an integral function of VQE software. AEC detects and removes the sender’s transmission from the recipient’s path while addressing the inherent variable packet delay. AEC on a VoIP network is particularly challenging because of the variable packet delay. Because of this, VQE algorithms used to reduce the echo are more computer-intensive than equivalent echo cancellation solutions for circuit-switched networks. However, proper VQE software can detect and eliminate the echo without affecting call quality or drawing attention to the customer.
Voice Quality Metrics: Having the ability to remove audio quality impairments is one thing; having an objective way to measure quality and monitor performance is even better. Voice quality metrics give contact center providers a standard way to measure audio quality and uphold service level agreements (SLAs). Part of the VQE software, the metrics capture statistics for three categories: 1) packets, monitoring packet throughput, loss, and delay; 2) audio, measuring speech and noise power levels; and 3) AEC, measuring echo delay and cancellation performance. By having these statistics available, service providers can continuously monitor audio quality performance, verify performance expectations, and identify any potential issues in the network.
Summary: Advancements in VQE software are enabling contact center services to overcome the audio challenges of VoIP networks. Software that provides noise gating, packet loss concealment, and AEC capabilities is enabling providers to offer the same audio quality as traditional circuit-switch networks, while also offering metrics to uphold SLAs and continuously monitor performance. Integrating VQE capabilities in an IP media server delivers an innovative and cost-effective approach for addressing the audio quality challenges of VoIP. By incorporating these technologies into their contact center networks, providers are able to realize the economic and technical benefits of VoIP networks while delivering the highest quality service to their customers.
Ray Adensamer is with Radisys, a provider of hardware and software for IP-based networks.
[From Connection Magazine – Jul/Aug 2011]