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Review: Polycom Spectralink 8002 Wireless Telephone

In Use

Two of the fundamental problems facing most Wi-Fi SIP handsets are cordless range and battery life. Simply put, Wi-Fi was not designed with conservation of power consumption as a top priority. So Wi-Fi radios tend to draw considerable power continuously, which can result in lackluster battery life. Ramping down transmit power isn’t a viable power conservation optione, either, since it limits range.

Happily, in the SpectraLink 8002, Polycom has elected to use a substantial NiMH battery. Polycom wouldn’t tell us the battery mAh capacity and there is no marking on the battery pack. But the specified talk time is up to 3 hours, with up to 50 hours of standby operation. I was happy to find that these claims were met over the period of my evaluation. I used the phone over a period of a few weeks without ever feeling that the battery life was a problem.

For heavy users, Polycom offers a charging stand that will charge both the handset and a spare battery, making it more convenient to always have a charged spare battery at the ready. I suspect that serious commercial users will find this option a necessity.

For pure data applications, a WLAN may be designed with spot coverage to provide a data connection to a bank of cash registers, for example. But if you intend to deploy Voice-over-Wi-Fi (VoWifi), then you’ll need good signal coverage over an entire facility.

To help in spotting RF coverage dead zones, the 8002 provides a handy site survey mode (Figure 5). This function provides a real-time readout of the RF signal level of your WLAN as you wander about your facility. When engaged in this mode, the LCD displays the ESSID, RF level, RF channel, WLAN type and security type. You can easily use this tool to map out any holes in your access point layout.

Figure 5: Display with phone in site survey mode

During the few weeks that I used the SpectraLink 8002, it generally served me well. WMM worked as promised; calls were never choppy because of data activity on the WLAN.

Voice quality was in general very good. I was also pleased to find that the handset provides a generous range of volume, which helps me when I’m working near loud server racks.

It takes a little time to get used to using the four function buttons just below the LCD. At first they appear to be two large elliptical buttons, but are, in fact, four separate buttons. Common calling functions like mute, hold, redial and transfer are easily accessed via these buttons.

Wireless QoS a.k.a. WMM

The 8002 has only an 802.11b radio, but it includes support for Wireless Multi-Media (WMM.) WMM is analogous to quality of service (QoS) in a network router, but is designed specifically for wireless networks. This kind of traffic management is required any time you need to ensure absolute continuity of streaming media over a wireless LAN.

When passing voice traffic over your network it’s important that the voice streams get the highest possible priority. This is handled through a mechanism known as “Quality Of Service” or QoS. The necessity of network QoS (or WMM on a WLAN) stems from the fact that in most VOIP installations the voice data (RTP streams) is transmitted using UDP, not TCP.

Within the TCP protocol, there are features that provide for retransmission of dropped or lost packets of data. Regardless of network conditions, all the data sent is received, no matter how long it takes.

Conversely, the UDP protocol does not provide for retransmission of unreceived data. Streaming media sent using UDP might actually lose some data packets to network congestion. The attempts to retry sending lost packets are dropped in favor of trying to maintain a low-latency, real-time stream.

Most network traffic is typically bursty in nature, but VOIP calls and streaming video are not. They are time-sensitive streams of data that need to remain continuous. Without any management of QoS (or WMM in the case of a WLAN) the simple act of checking for email can cause audible breaks in an ongoing phone call. The email client fetching messages can momentarily create a burst of network traffic that saturates some portion of the network. The end result is lost voice packets, and poor voice calling experience.

Polycom is very clear that the 8002 absolutely requires WLAN hardware supporting WMM. So I acquired a new WMM-capable Netgear WNR854T router/AP to replace my very old Linksys WAP54G.

The Polycom 8002 supports both alpha and numeric dialing. It’s much simpler to dial by number from the phone itself, but one can enter a SIP URI directly if required. I found it easier to use SIP URIs in the “favorites” loaded from the provisioning server rather than entering them on the handset manually.

My home and office comprise an area of around 18,000 square feet. With one access point located in my home office, I found that I could reliably use the handset in about 70% of the property. If I were to relocate the access point to a more central position on the property or add a second access point I’m confident that I could use the phone across the entire property.

With the single access point, the useful range of the phone was just a little less than what I’m accustomed to using DECT cordless phones, but considerably more than any previous Wi-Fi handset I have used. I expect that this is as much a result of the newer wireless router as the phone itself.

This Post Has 3 Comments
  1. Hi MIchael,

    It sounds like the server based config files differ from the wired Polycom IP phones in both format and execution. User credential based vs. MAC based? True?

    thanks.

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