Posted on 9-Oct-2008 15:13 by S Biddle|
Filed under: Reviews
With Voice over IP telephony now being mainstream the number of VoIP phones in the marketplace has grown significantly over the last few years.
While there are large numbers of VoIP desk phones in the marketplace the options for cordless phone replacements has been quite limited, with only a small number of handsets making it to market and many of these having suffered from issues such as poor battery life that have slowed their adoption.
As the market has evolved handsets manufacturers have gone down two different technology paths – WiFi and DECT. WiFi phones connect directly to the SIP proxy via WiFi Access Points while DECT based solutions use a DECT air interface to connect to a DECT base station which in turn registers with the SIP proxy via an ethernet connection.
There are advantages and disadvantages to both technologies with DECT’s telephony based architecture arguably offering an advantage over WiFi in both call quality and call handover between access points. WiFi on the other hand can deliver a greater number of calls per base station, is easily scalable, and can also allow concurrent voice and data which avoids unnecessary infrastructure duplication.
If you have a multisite environment the advantage of WiFi is obvious – wherever you have WiFi coverage across multiple sites users can make and receive calls seamlessly. Discussing the advantages and disadvantages of both technologies isn’t what this review is about however – it is something that you do need to discuss with your system integrator if you are looking at deploying cordless phones in a VoIP environment.
The Polycom Spectralink 8002 is Polycom’s newest WiFi handset. Unlike other earlier Polycom models that were aimed at the enterprise market and required enterprise grade access points, this new phone is aimed solely at the small/medium business market and will work on any WiFi access point that supports the WMM (Wireless MultiMedia) protocol.
In the past WMM has typically only been available on high end routers and access points but is now available on most consumer grade routers in the marketplace. WMM ensures Quality of Service (QoS) so that voice traffic is given priority over non voice traffic over the WiFi connection so that call quality is not sacrificed by other WiFi traffic.
The handset it self weights in at 119g and measures 140mm x 51mm x 23mm. The unit is very well built with a plastic housing that feels very robust. The keypad and function keys on the side of the phone have a nice feel to them but the keypad does require quite firm pressure.
The bottom of the handset features a standard 2.5mm audio connector for a standard headset. Battery life without making any calls was around 40 hours and around 2.5 hours of continuous talk time. The battery clips onto the back of the unit and is easily changeable if additional batteries are purchased to extend the talk time. Polycom also have a range of belt clips and pouches available for the handset which are available as optional extras.
Setting up the phone isn’t particularly difficult but reading the administration manual beforehand is highly recommended! This phone cannot be provisioned from the keypad or web interface, instead it follows along the line of existing Polycom phones and downloads its configuration files from a TFTP server every time it is switched on. The first step is to connect the phone to your WiFi network, to do this you need to manually enter the ESSID and encryption key into the handset itself using the keypad. The phone supports WEP, WPA and WPA2 encryption with a preshared key but does not support RADUIS.
If your network supports Option 66 for DHCP then the phone will automatically be allocated an IP address by your DHCP server and will then connect to your TFTP server and download its configuration file. If your network doesn’t support Option 66 then you will also need to manually enter the networks settings (IP address, subnet mask and gateway) as well as the IP address of the TFTP server into the handset using the keypad. Entering your SIP extension and password can also be done from the phone menu but the phone also allows you to configure the extension settings every time you power the handset on if you wish, we’ll cover more about this later.
On your TFTP server you will require Spectralink 8002 firmware files and configuration files which are available from the Polycom website. Two configuration text files are required – sipusers.cfg contains the proxy details of your VoIP PBX while the SIP extension and password are located in their own file in the format sip_.cfg, ie sip_211.cfg. There are also a number of other configuration options and these are all set in these files. The following files work great with my Asterisk PBX at home.
If you had previously entered a SIP login and password of 211 then the phone will authenticate this against the details contained in this file and will always remain provisioned as extension 211. If you chose not to configure a SIP login in the handset you will be prompted to enter a SIP login and password every time the phone is turned on.
The beauty of this is that it allows a phone to easily be shared between users who all have their own extensions (such as shift workers) as they simply enter their SIP extension and password and the phone is provisioned for their own extension and by simply turning the phone off and on again it’s ready for use by another person.
The phone also features an internal phonebook that is configured in these files and is downloaded to the handset every time it is turned on. The handset only supports G.711u (ulaw) and G.711a (alaw), it has no support for other common codecs such as G.729 which is quite surprising, particularly in a wireless environment where the reduced bandwidth requirements of a compressed codec such as G.729 could be beneficial.
The handset features a great site survey mode that will display the current signal strength of all nearby AP’s. It also feature a syslog option that if enabled can upload call data to a syslog daemon running on your network. This log contains network related information along with signal strength and call jitter which is a very valuable tool for analyzing the performance of your phones. Other features are fairly standard including manual keylock, automatic keylock function with adjustable times and one touch access to voicemail, phonebook and call forwarding. Microphone sensitivity is also adjustable between normal, high and severe depending on background noise. The phone supports up to 5 lines and has a dedicated line button on the bottom to select the outgoing line you wish to use for the call.
In all my testing both call quality and volume levels were superb and battery life was great. One thing I was keen to test was the ability of the handset to support handovers between multiple WiFi access points, this is something that can be an issue as packet loss can occur as the device disconnects from one access point and registers with the other.
In my tests involving several different brands of hardware I was very impressed, at times there was minimal audio loss but it would probably not be noticeable to somebody who wasn’t listening out for it.
Overall I was very impressed by the performance of this handset and over several weeks of daily use really found it hard to fault. Provisioning and setup may prove slightly cumbersome for some users but once you understand exactly how this works setting up the handsets is extremely simple.
The user interface was very straight forward and overall made using the phone a very pleasant experience.
• Great form factor
• Great call quality
• QoS using WMM worked well
• Belt clip not included – comes as an optional extra
• Only supports G.711a and G.711u – no G.729 or other compressed codecs
• No missed call register