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Product Reviews
October 2002

Converged Telephony Platform

Comdial Corporation
106 Cattlemen Rd.
Sarasota, FL 34232
Web site: www.comdial.com

Price: Turnkey Converged System for 100 users with trunks, phones, and unified messaging: $400 - $800 per user.

Editor's Choice Award

Installation: 4.75
Documentation: 4
Features: 4.5
GUI: 4.25
Overall: A-

Choosing your next PBX is one of the most important decisions a company can make that will directly impact employee productivity. In these lean economic times, ROI is often the critical factor in deciding whether to keep an older PBX or replace it with a newer one. In the past, CTOs/CIOs would justify purchasing a new PBX based on such productivity-enhancing features as unified messaging, ACD functionality, hunt groups, and predictive dialing. However, employee productivity is something very difficult to gauge. Not so with IP-PBXs. IP-PBXs often have a clear ROI due to their associated cost savings when routing calls between branch offices via VoIP with no long-distance charges incurred. As such, a CIO/CTO can justify to the CFO the need for a new IP-based PBX in hard numbers.

One such company in the IP-PBX realm is Comdial, well known for their traditional PBX product line. Their newest PBX offering -- called the Converged Telephony Platform (CTP) -- features unified messaging, ACD functionality, desktop call control, and more.

Based on a modular hardware and software architecture, CTP consists of Comdial�s FX II Business Communication System, its Interchange Unified Messaging Solution and its Impact Attendant eConsole. The FX II simultaneously supports traditional voice features and IP telephony. Comdial�s Interchange UM Solution offers unified messaging as well as extensive call processing capabilities.

Desktop Call Control
Comdial�s strength has always been in its CTI-support and CTI applications, including desktop call control. We tested Impact Attendant, a graphically rich interface that receptionists will find invaluable. It displays the current status of a select list of phone icons on the screen, such as on the phone, off hook, and on-hook. Transferring, parking calls, and creating a conference is a breeze using this application.

Trunk/Extension Testing
To test Comdial�s trunks we connected the CTP to our Gordon Kapes T1/E1/PRI simulator. After some minor troubleshooting we were able to get the two to synchronize. We then used an analog phone connected to the Gordon Kapes to dial into Comdial CTP. The voice messaging system answered promptly and we were able to dial and connect to an extension with no problems. We repeated this test multiple times with no failures. We should point out that the CTP supports both Comdial�s VoIP phones as well as their traditional digital phones. Thus, any organization with an investment in Comdial�s digital phones can retain their use. We made calls from VoIP phone-to-VoIP phone and digital phone-to-VoIP phone and they both performed flawlessly with excellent voice quality. Later in our tests we measured the VoIP latency.

Voice And Unified Messaging
While testing trunk support we also tested the voice messaging system. We left several test messages, which showed up both on the Comdial LCD display (number of messages) and our Outlook Inbox. One nice feature is that using the Comdial phone you can screen callers leaving a message in voice mail and pull them out of voice mail if desired.

We liked the fact that Comdial supports both a �single message store� (true unified messaging) as well as a �dual message store� (integrated messaging) where voice messages are stored on both the Comdial voice messaging server and the Exchange Server with synchronization performed between the two. Even better, choosing one or the other can be selected on a per-user basis based on the user�s preference or the IT manager�s discretion.

One of TMC Labs� pet peeves is a unified messaging product that requires you to double-click on a message in the inbox followed by a single-click on the play button. The voice message should auto-play after double-clicking on it. The extra click is redundant -- why else would you be opening the voice-message? We�ve seen this countless times and we�ve criticized it every time. Fortunately, Comdial escaped our wrath as it does auto-play after double-clicking on a voice message. Note that Comdial includes an embedded multimedia player. You are not required to use their player, but the advantage of using Comdial�s player is that you can switch between phone and sound card playback as well as pre-pend (or post-pend) a recorded message to the original voice message.

Call Center Features
The CTP supports �whisper mode,� (Comdial refers to it as SOHVA, or Secure Off-Hook Voice Announce), which enables a user of the system to �whisper� to a user who is on the phone that the remote caller cannot hear. This is particularly useful in call center environments where the call center manager may supervise or coach the agent while on the call. In addition, the call center manager can �silently� monitor agents� calls.

Also, Comdial�s Interchange UM offers Enhanced Customer Service (ECS) functionality, which is designed to optimize call center operation. When integrated with Comdial DSU II, DXP, and FX series telephone systems, ECS provides capabilities such as flexible call distribution, call queuing, and agent administration.

To measure latency, we made a call from one VoIP extension to another. We set both Comdial phones on speakerphone with the �receiving� end phone microphone muted. Then, we placed a PC microphone located near the vicinity of the �transmitting� end phone, which would mark the �start time� for when the sound was initially transmitted. Using CoolEdit we could record the initial sound energy coming into the PC microphone, which is the exact moment it also enters the transmitting end phone. The sound packets traveled across our test network and reached the �receiving� end phone and were played over the phone�s speakerphone. These sounds then traveled back into the PC microphone allowing us to determine when the sound packets reached their destination. By measuring the distance between the start and end times in the waveform, we were able to calculate the latency. 

Using the G.711 codec, we measured an average latency of 216ms, which is fair, but not great. Next, using Comdial�s main administration program, called VMMI, we changed the IP Link boards to use G.729ab. Using the compressed G.729ab codec, we measured 417ms latency, which is a bit slow.

Finally, we were curious if the latency of a VoIP phone-to-VoIP phone call was greater or less than a VoIP phone-to-digital phone call. Thus, we measured latency of sound traveling from VoIP phone-to-digital phone and digital phone-to-VoIP phone using the G.711 codec. We noticed no difference in latency when transmitting sounds from a VoIP phone to a Comdial digital phone (216ms). However, we did notice that the latency was slightly better (206ms or 10ms faster) when transmitting sound from a Comdial digital phone to a VoIP phone.

VoIP Protocols
Comdial doesn�t support the H.323 protocol, so you can�t use NetMeeting as a �PC-softphone� alternative. Currently, Comdial uses their own VoIP protocol, however SIP support is planned. Since the phones are �firmware upgradeable,� the SIP stack will be a simple download. Comdial told us they�ve done some beta testing with Microsoft�s SIP-based MSN Messenger, which will allow for a �PC-softphone.�

Within the VMMI management program it should show the previous setting in case something gets screwed up. Also, maybe a �master view� displaying ALL previous settings that have changed. Basically we�d like to see a �delta� consisting of all the last changes. Perhaps even store the last 10 changes by time/date, so the administrator can figure out not only what broke it, but also how to undo it.

Another suggestion for the VMMI would be to have the GUI in a tree-like structure. It�s much easier to get back to prior screen the user was viewing. Comdial told us they are working on a Web-interface that has a �Back� and �Forward� button -- certainly useful for navigating back and forth between two setting screens.

Finally, we noticed if we unplug the IP-PBX from the network, all calls go down, including internal extension calls. We feel that internal calls should still work simply by adding �peer-to-peer� support to the VoIP phones. Essentially each phone would have a mini-gatekeeper for looking up the IP address of a particular phone extension. Also, after plugging the IP-PBX back onto the network it took a total of 65 seconds for the phones to become functional again. We noticed that each phone reloads the firmware whenever the IP-PBX is disconnected. The phone should just re-establish a connection immediately without having to reboot. The only time the phone should need to boot up is on initial connection or if the phone itself is having a problem; not when the IP-PBX is disconnected.

Comdial�s Converged Telephony Platform is perfectly suited for small and medium-sized enterprises allowing them to cautiously deploy integrated voice/data IP applications when it is prudent to do so. We liked the Comdial phones, which are very ergonomic, and which have very functional LCD displays. The fact that Comdial made the phones firmware upgradeable is a critical feature. We look forward to checking out their SIP firmware release in the near future. The voice messaging system and specifically the unified messaging functionality were superb. Overall, Comdial�s Converged Telephony Platform performed well in our tests and we were quite pleased with its plethora of features, which allowed us to grant our Editors� Choice Award without reservation.

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