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					Network Magazine | The Incredible VoIP Solution | June 1, 2005                                                                        Page 1 of 3

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   The Incredible VoIP Solution
   We asked top Industry Experts to design the perfect telephony system. Here's what they came up with.

   By David Greenfield
   06/01/2005, 12:00 AM ET                                                                                                Utilities
   Incredible Applications For Incredible Phones                                                                          Print this article
                                                                                                                          E-mail this article
   What constitutes the ideal IP telephone? Mobility? Lots of buttons? Integration with enterprise applications?          License this article
   Everyone has their own opinion of what makes the perfect IP phone and VoIP implementation, but we've gone              Discuss this article
   a step further. In this month's Convergence, we've enlisted the help of four experts to come up with the ideal IP
   phone and VoIP network architecture.
                                                                                                                          Related Links
   Together they've composed a list of requirements that should be on anyone's shortlist for desktop phones.
   They've also designed an elegant VoIP network that you can use as a template when planning your own VoIP            The Incredible
   deployment.                                                                                                         Telephone

   Not surprisingly, one of the features they flagged for the ideal IP phone was a large display. A decent screen      The Incredible
   makes it possible to view a corporate and personal phone directory that includes real-time presence                 Remote Office
   information. A sizable screen also lets users run third-party applications. At a recent Cisco Systems partner
   conference, for example, I stumbled across one application that allowed users to control their conference room      The Incredible Panel
   environment, giving them the ability to activate a projector, adjust the room temperature, or lower and raise the
   blinds at the touch of a button. Sure, you could run that sort of application on a PC, but not all conference
   rooms have a PC. They all have telephones, however.                                                                 The Incredible VoIP
                                                                                                                       Architecture                                             6/22/2005
Network Magazine | The Incredible VoIP Solution | June 1, 2005                                                                       Page 2 of 3

   INTO THE OFFICE                                                                                                        Letters
                                                                                                                          SIP Goes Peer-to-
   It's true that broader, mass-market applications could be created for those phones, but that won't happen              Peer
   anytime soon, in part because each manufacturer has its own development environment. This lack of                      The 2005 Network
   interoperability narrows the market scope for applications and forces developers to recode software for each           Magazine Innovation
   environment, which ultimately leads to higher prices and more limited choices. Third-party development kits            Awards
   from the likes of Millenigence or Citrix can be used to smooth over these differences, but not without adding          Location-Aware
   cost and complexity to the IP telephony system.                                                                        Networking: We
                                                                                                                          Know Where You
   As Art Wittmann points out in this month's Foundations (see page 8), the real difference between companies in          Are
   the networking industry today isn't in their intellectual property, but in their execution of ideas that are already   Taking VoIP to the
   fairly widely understood. The same holds true for telephone-based applications. If all high-end phones from            Movies
   major telephony manufacturers can run hospitality and other vertical applications, then the real difference            Assuring VoIP
   between those phones isn't really in the applications, but in the telephone's packaging and design.                    Quality: Not There

   If the industry is serious about making those silver-screened phones more than just eye candy, then it needs to work together to form a
   common development environment. Heresy? Hardly. The first steps toward common standards for IP phone applications have already
   been taken. The Wireless Markup Language (WML) used by the mobile industry for creating applications on mobile phones has been
   adopted by at least two IP telephony vendors: Avaya, in its new IP phones; and Siemens, in its OptiPoint phones.

   But WML alone isn't enough. For one thing, Cisco still uses its own Cisco XML, not WML, on its phones, while Nortel Networks'
   applications require Citrix technology. What's more, as with the Session Initiation Protocol (SIP), vendors have written their own
   proprietary extensions to WML. Thus, while standardized core functionality is set, more advanced features such as enhanced scrolling
   are still specific to each environment. As long as those differences remain, display telephones may continue to gather a lot of foot traffic
   at trade shows, but they won't win much mindshare at the desktop.

   By now it's become a mantra: The Session Initiation Protocol (SIP) is the future of VoIP. The vendors are saying it, and the network
   designers are building for it. Even Cisco Systems, the only major VoIP vendor not to offer native SIP client support, will add the
   capability to its next major release of Cisco Call Manager expected at the end of the year. All this begs the question, just what should
   network architects be considering when they evaluate an IP PBX?

   To answer that question, we assembled a panel of leading VoIP architects and designers and asked them to compose a wish list of ideal                                            6/22/2005
Network Magazine | The Incredible VoIP Solution | June 1, 2005                                                                         Page 3 of 3

   telephony requirements (see "The Incredible Panel"). Together, the group mapped out exactly what the Incredible VoIP Architecture
   should look like. They defined the core of the SIP network--the call-stateful proxy--and prescribed the resiliency, scalability, and E-911
   features that such a proxy should deliver. The panel also took into account the remote office, defining an integrated device that provides
   both remotely managed VoIP and the right mix of security functions. No VoIP solution would be complete without effective
   management, of course. The panel's ideal VoIP management solution not only integrates with the existing management infrastructure,
   but allows network architects to define global policies for the telecom network, as well as specify configurations for particular call

   As for the Incredible Telephone, our team eschewed the large color displays of high-end models where videoconferecing was concerned.
   "You don't get anything useful in interactive communications with a 4x7-inch display. You just get an expensive toy," says Brian Rosen,
   one of our panel experts. (Using the display for phone-based applications is another matter, however.) Our panel also wanted SIP phone
   sets that didn't use proprietary SIP extensions. Those phones should be able to fail over to a backup power supply or an alternative SIP
   proxy and offer better-than-PSTN voice quality.

   In all, the Incredible VoIP Solution borrows elements from many of today's VoIP systems and mixes them with some features and
   functions not yet seen. The solution's fully distributed design can be seen on a smaller scale in ShoreTel's VoIP architecture, while the
   notion of a stateful SIP proxy capable of supporting tens of thousands of IP or analog endpoints is more reminiscent of Siemen's HiPath
   7000 or Zultys Technologies' Enterprise Media Exchange server. In terms of diagnostic functions, many of these capabilities can be
   found in advanced management platforms such as that from Avaya. The emphasis on a single remote device at the remote office falls in
   line with Cisco's Integrated Services Router line, while Mitel Networks' 5230 IP Phone is probably the closest to the Incredible

   Yet for all its similarities to the big VoIP systems on the market today, the Incredible VoIP Solution breaks new ground in many areas.
   Its fully distributed and open architecture is, if not unique, at least rarely offered in highly scaleable corporate IP telephony products. The
   extensive use of presence technology foreshadows the type of IP phones that will be possible in years ahead. Even minor details, such as
   improving reboot times by downloading configuration updates rather than the full configuration files, are something that many VoIP
   systems still lack today.

   Executive Editor David Greenfield can be reached at

| 1 | 2 | Next Page > >                                              6/22/2005
Network Magazine | The Incredible VoIP Solution | June 1, 2005                                                                        Page 1 of 3

                                                                                                          Free Magazine Subscription
                                                                                                    Free Newsletter Your Email
                 Channels: Compliance | Wireless | Convergence | Security | Data Center

  Current Issue | Past Issues | Channels | Forum | Contacts | Site Map | RSS | Blog                                              | advanced

   The Incredible VoIP Solution
   We asked top Industry Experts to design the perfect telephony system. Here's what they came up with.

   By David Greenfield
   06/01/2005, 12:00 AM ET                                                                                                Utilities
   The Incredible VoIP Management System                                                                                  Print this article
                                                                                                                          E-mail this article
   The Incredible VoIP Management System should integrate with the general network management system, as                  License this article
   well as provide the necessary tools to configure, manage, and troubleshoot a VoIP network. More specifically,          Discuss this article
   the VoIP management system should use identities contained within the corporate LDAP database and the
   company's identity management solution (for example, Microsoft's Identity Integration Server). This simplifies
   the configuration of roles, access rights, and policies in the VoIP solution.                                          Related Links

   Telephony vendors tend to emphasize the benefits of treating the VoIP system as a single entity, but our panel      The Incredible
   favored a different approach. VoIP policies, such as those regarding dialing-plan information, should be            Telephone
   expressed network-wide. However, configuration information is server-specific and requires the ability to alter
   port settings and configuration parameters individually for each server. Thus, as part of that configuration        The Incredible
   process, network managers should be able to place restrictions on what users can do. This includes limiting the     Remote Office
   use of voice, video, and data sharing or IM during a call; the number of users participating in a given call; and
   the number of simultaneous calls that a user can establish. The system should be able to determine the right        The Incredible Panel
   codec to use on each call based on the available bandwidth and the type of user.

   The importance of the converged solution also means that management solutions should be able to detect a            The Incredible VoIP
   failing system and re-assign users before they notice. Problem detection requires that statistics be gathered       Architecture                                             6/22/2005
Network Magazine | The Incredible VoIP Solution | June 1, 2005                                                                 Page 2 of 3

   directly at the end-client, particularly when it comes to detecting NAT problems. SNMP can be used for this       Letters
   task, but polling for SNMP traps across thousands of nodes won't scale well, notes panel expert Walt              SIP Goes Peer-to-
   Magnussen. Better still would be to set thresholds at the devices using the RTP Control Protocol Extended
   Reports (RTCP XR) standard and alert the management station when those thresholds are crossed.
                                                                                                                     The 2005 Network
                                                                                                                     Magazine Innovation
   Finally, ensuring that the system will scale properly requires system capacity planning tools. In the TDM         Awards
   world, life was easy. "You had time slots or ports, and when you ran out you ran out," says Magnussen. Now        Location-Aware
   with VoIP systems consisting of multiple servers, scaling has become more complex. It's simply not enough to      Networking: We
   add memory and processing to a user's proxy server. Depending on the VoIP configuration, those same               Know Where You
   variables may need to be tweaked elsewhere, such as at proxy servers responsible for routing traffic, location    Are
   servers, conference servers, redirect servers, and registration severs. Layers two and three parameters such as   Taking VoIP to the
   QoS settings and bandwidth allocation may also need adjusting.                                                    Movies
                                                                                                                     Assuring VoIP
                                                                                                                     Quality: Not There

   The Incredible VoIP Architecture

     Also see the Online Extra, The Incredible SIP RFCs                                      6/22/2005
Network Magazine | The Incredible VoIP Solution | June 1, 2005                               Page 3 of 3

   The Incredible Panel

   The Incredible Remote Office

   The Incredible Telephone

< < Previous Page | 1 | 2    6/22/2005 (1 of 2)6/22/2005 1:11:49 AM (2 of 2)6/22/2005 1:11:49 AM
The Incredible SIP RFCs

Here are the RFCs that panel expert Henning Schulzrinne thinks an Incredible Converged Phone System should implement:

RFC Number      Site                                            What's Defined                    Why It's Incredible
                                                                                                  It's the basis for convergence today. Isn't that
3261             The SIP protocol                  enough?
                                                                                                  SIP is a distributed protocol. It's not much use if
                                                                                                  SIP servers can't find one another. The protocol
                                                                How SIP servers can find one      is also used for DNS load balancing between SIP
3263             another                           servers
                                                                Extensible framework for SIP      For applications to work, self-awareness is nice,
                                                                nodes to request information      but knowing what's happening across the
                                                                from other nodes about the        network is even better (for example, a change in
3265             occurrence of an event            presence status in a buddy list)
                                                                                                  A major way for clients to find a SIP server is by
                                                                                                  querying a DHCP server. This is the protocol that
                                                                                                  explains how to put SIP server addresses in
3361             DHCP for SIP                      DHCP for IPv4
                                                                                                  Life changes and so do SIP sessions. UPDATE
                                                                                                  allows a SIP client to change the parameters of a
                                                                                                  session, such as when it wants to add voice to
3311     UPDATE command                    an IM session
3428     MESSAGE command                   Used as the basis for IM over SIP
                                                                                                  Used as the basis for call transfer and all
3515     REFER command                     telephony operations
3319             DHCPv6                            Same as 3361, but for IPv6
                                                                Advanced Encryption Standard Explains how to apply the AES encryption
3853             (AES)                             algorithm to SIP messages
                                                                                                  Explains how SIP user agents (telephones) can
                                                                                                  inform one another about their capabilities, such
                                                                                                  as the ability to support video calls or whether
3840             UA capabilities                   they have an auto-attendant
                                                                                                  A set of extensions that express a policy for how
                                                                                                  incoming calls are treated, such as being sent to
3841             Caller preferences                voice mail
                                                                                                  Explains how to do call control, such as attended
3891             Replaces                          transfers
                                                                                                  A way of referring other SIP user agents to
                                                                                                  another SIP address or URI. This approach is
3892             Referred-By                       needed from some call transfer scenarios
                                                                Authenticated Identity Body (AIB) Adds S/MIME to SIP message to protect the
3893             format                            message headers
                                                                                                  A language used for controlling telephony
3880             Call Processing Language (CPL) services in proxy servers
                                                                                                  The protocol that actually makes the phone talk--
                                                                Real-time Transport Protocol      that is, by transporting voice and video bits
3550             (RTP)                             across the network
                                                                Presence Information Data         A standard way of expressing presence
3863             Format (PIDF)                     information
                                                                A Presence Event Package for      A way of subscribing to and being notified of
3856             SIP                               changes in one's presence status
                                                                                                  An XML document format listing the buddies that
3858             Watcher information               are watching you
                                                                                                  A way of knowing in an IM message whether
                                                                                                  individuals are typing a response message to
3994             IS-Composing                      you (1 of 2)6/22/2005 1:13:11 AM (2 of 2)6/22/2005 1:13:11 AM (1 of 2)6/22/2005 1:13:26 AM (2 of 2)6/22/2005 1:13:26 AM (1 of 2)6/22/2005 1:13:43 AM (2 of 2)6/22/2005 1:13:43 AM

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