Not so long ago, I wrote an article on Asterisk and open source VoIP in general. In my discussion with Mark Spencer, the founder of Digium and the Asterisk project, he recommended Polycom as the phone vendor he would choose for an Asterisk deployment. In the same article, I profiled Summer Bay Resorts, which runs Asterisk across multiple call centres and hundreds of agents, all with Polycom phones. You might think Polycom is onto something.

Polycom is known to most as the producer of the "boomerang" conference room speakerphone. With their instantly recognisable tricorn shape, these phones can be found in nearly every conference room. The rest of the product line hasn't received the same level of attention, but my time with the Polycom SoundPoint IP 650 executive phones shows that they deserve it. In addition to its wired sets, Polycom recently acquired SpectraLink and its VoIP Wi-Fi technology. I tested several SpectraLink Wi-Fi sets, a few IP 650 sets, and yes, the VoIP version of that ubiquitous speakerphone.

All three phones were tested with Asterisk running under Trixbox 2.0, and used with a variety of trunks, from ATA (Analogue Telephone Adapter) bridges to the PSTN to pure SIP trunks served via BroadVoice. As with all VoIP phone tests, I tend to use my Cisco 7970 phone as the touchstone, since it's arguably the most advanced IP phone available on the market today.

There's still plenty of room to grow in this space, and as of yet, I haven't found the truly perfect VoIP phone. Given that VoIP roll-outs require a variety of phone types to meet needs throughout the enterprise, standardising on a single phone vendor is really the only way to go. It means less hassle, easier configuration, and smoother implementation. Collectively, these units show that Polycom is serious about VoIP and SIP telephony. The Polycom line has a little something for everyone, including lower-end handsets that I didn't test for this article. Especially in an Asterisk environment, Polycom phones are clear winners.

No. 3: SpectraLink NetLink e340 wireless handset

There are many Wi-Fi VoIP handsets on the market now, running the gamut from the low-end consumer devices from Linksys and ZyXel to high-end corporate devices from Cisco and SpectraLink. These phones generally follow the same basic configuration path as their wired counterparts but require more device-specific configuration to allow them to gain access to the network, such as specifying the encryption type, ESSID, and passwords. Generally, they're also stand-alone units. The SpectraLink e340 fits the former generalisation, but not the latter, as it works with a SpectraLink Voice Priority (SVP) server and supported access points to ensure good voice quality.

The handsets are sleek, with a small LCD screen, a few multifunction soft buttons, and a charging base. Initial configuration of the phones is handled locally, and the phones can be assigned static IP addresses or get them from a DHCP server. In addition to the normal network configuration, you must also enter the IP address of an SVP server. The SVP server is a proxy server for the phones, acting as an intermediary between the SIP PBX and the phone itself.

The SVP server is an odd box that doesn't conform to any common IT hardware standard -- it won't fit nicely in a rack, for instance. It runs embedded Linux, and it has only a single tip-and-ring power connection and a single network connection. When a handset boots and contacts the SVP server, the SVP server then connects to the SIP server using another dedicated IP address. This means that each handset requires two IP addresses: one for the handset itself and another for the proxy connection to the PBX. From the PBX point of view, the extension is on an IP assigned to the SVP server, not the handset. This allows the SVP server to handle a variety of QoS tasks. Working with compatible access points, it pushes VoIP traffic to and from the handset to the top of the queue, ensuring that the latency-sensitive packets are delivered in a timely fashion. This results in better call quality and assists in AP roaming functions. The mechanism is a bit ungainly, but it serves a useful purpose. Further, multiple SVP servers can be configured in a redundant fashion.

Call quality on the e340 is good, assuming that the unit is reasonably close to an access point. Drifting further from the AP can result in transmitted voice taking on a "Donald Duck" tone while received audio is still clear and crisp. I also noted that the handsets will hang onto a distant AP longer than they should when another AP is closer. And the e340s are quirky to use. The soft buttons are not only very small, but require significant pressure to trigger. That said, my inclement weather test (basically, leaving a handset out in the rain overnight) resulted in some misting of the LCD screen, but no other ill effects. This certainly isn't a recommended use of the phones, but it's nice to know that a little water won't necessarily kill a handset outright.

Battery life is good. I conducted conversations lasting several hours with these phones without any problems. Also, they don't get nearly as hot during normal operation as some other Wi-Fi VoIP handsets, which is a definite plus. A hot phone is not conducive to normal conversation. The e340 does have a standard minijack at the bottom for a headset, though I did note some quality loss when using a Plantronics headset. And try as I might, I couldn't get the message waiting indicator to trigger on the e340. It's represented as an icon on the LCD screen, but it doesn't seem to work with Asterisk.

I've tested and used a variety of Wi-Fi VoIP handsets, and the SpectraLink NetLink e340 is right up there in terms of overall quality, ruggedness, and performance. I found a few minor annoyances and quirks, such as the difficult buttons and odd SVP server footprint and dual-IP scheme, but overall it's a worthy product.


A rugged, high-quality Wi-Fi VoIP handset that performs very well, despite a few quirks.