The Challenges of Enterprise IP

Electronic News, August 20, 2001 by Debbie Greenstreet, Melissa Carman

THE LATEST ENTERPRISE IP phone solutions are promising but come with their share of challenges. These solutions leverage not only the latest voice-over-Internet Protocol (VoIP) standards and IP technology, but the latest DSP technologies as well. This next generation of IP telephony equipment will include enterprise IP-based telephones to execute functions currently performed by proprietary PBX-based telephones as well as to tap into a vast new array of applications enabled by the Web. Integrated DSP silicon and VoIP software solutions will be a significant element in the new enterprise IP phone core technology.

Before these DSP-based solutions are widely adopted as viable options in enterprise telephony systems equipment, there are some key challenges that must be overcome. Fortunately, today's successfully deployed VoIP gateways, switches and CPEs have solved many of the implementation issues facing Enterprise IP phone architectures, helping to reduce the risk in meeting the quality and time-to-market necessary for market penetration.

Still, four key implementation challenges remain. First, the core solution must meet critically low price-points and offer features that are currently unavailable to justify the deployment over currently available PBX telephones. Second, Enterprise IP phones must exhibit voice quality equal to or better than traditional PSTN networks. Features must meet today's standards and requirements, and scale to add new features and standards. Lastly, with the availability of integrated IP phone solutions, IP phone vendors will be competing to rapidly deploy IP phone products.

The Voice Interface provides the conversion of analog voice, from a handset or microphone, into digital samples via a codec. Similarly, the processor passes a data stream in the return path to the speaker through the codec to convert digital samples back into speech to the handset's ear-piece or speaker. A single codec supports a handset for a basic phone capability.

The Network Interface allows LAN transmission and reception of voice packets from/to the telephone. For corporate LANs this is most often either 10BaseT or 100BaseT Ethernet running TCP/IP protocols. To avoid infrastructure rewiring, the IP telephone should offer a second RJ-45 Ethernet connector to allow a PC to plug in and share one connection to the wall jack.

The user interface provides the traditional user display and call management functions of a telephone. At a minimum, this consists of a keypad for dialing numbers and an audible indicator for announcing incoming calls to the user. A small screen is also typically provided for displaying user prompts, number dialed, CallerID information, etc. The user interface is the key differentiator for most OEMs.

The processor core is the heart of the IP phone and performs the voice processing, call processing, protocol processing, and network management software functions of the telephone. The voice processing features, consisting of compression, echo cancellation and tone generation, are signal processing functions, which are executed on DSPs. The call processing, protocol translation, network management and user features are typically general processing functions that are performed on a RISC or other microcontroller processor.

While all of these functions can technically be performed in either type of processor, critical development issues as well as performance limitations can arise when implementing certain features on a less-than-optimal processor type. DSP solutions are widely used today and have been highly optimized for signal processing functions. The DSP is the most efficient engine to execute these voice-related features and will use fewer processing cycles than other processors. This translates to less silicon required and smaller code size, resulting in less voice processing memory required; both key factors in reducing the IP phone solution cost to a minimum.

The opportunity to achieve greater-than-toll-quality voice in IP phones can be achieved by utilizing wideband voice codecs. Both of these features require signal processing algorithms, and are processed most efficiently on a DSP. The IP phone processor architecture therefore consists of a reprogrammable DSP for the voice and signal processing functions and a microcontroller unit for the remaining functions. Reprogrammable DSPs play an important role in meeting the challenges of enterprise IP phone solutions by providing a foundation for optimal voice processing as well as allowing for flexibility in product updates and growth.

Debbie Greenstrett is the director of product management at Germantown, Md.-based Telogy Networks, a Texas Instruments Inc. company. Melissa Carman is the IP phone product manager for Telogy.

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