4. Performance

Both products were downloaded and set up successfully, and both 'just worked' from behind my Linksys WRT54G router. Additionally, I set up the two products on a second network behind an old Siemens SpeedStream 2604 router and similarly experienced no problems at all connecting. SIP has a history of not working from behind a firewall or router, and so it was interesting to note that I experienced no problems with Gizmo in either configuration.

Figure 4: Skype and Gizmo in action.
(Click image to enlarge)

As expected, the quality of calls with both Skype and Gizmo varied greatly depending on the connection speed and traffic of the networks they were used on. In order to test the call quality for each product, I performed four tests: calling someone in the same city, calling someone in the same country, calling someone in another country, and establishing a conference call with two other people. These tests were first performed with no traffic on my end, and then performed while downloading four torrents (with a total downstream speed of around 400kb/sec and an upstream speed of 25kb/sec on a cable modem). I relied on my own impressions and the impressions of my fellow conversationalists in order to give me a good idea of the quality of the calls.

The call quality for the two products was more or less the same for each of these tests while no traffic was present. The addition of torrent downloads created a significant performance hit for both products, but Skype seemed to withstand the rigors of increased traffic more effectively, offering fewer jitters and dropped packets than Gizmo did. It is important to note that, even with downloads present, the two products' call qualities were generally on par with a cellular phone call. This was reinforced by an ironic situation in which, as my friend and I were discussing the unreliability of VoIP calls on our cell phones, the connection between our phones was dropped.

Both Gizmo and Skype have call quality indicators to help diagnose call problems. Gizmo's (Figure 5) is similar to the reception 'bars' on a cell phone, sitting at the bottom of the program window and providing an indicator of current performance. While not always the most accurate indicator (given that overall call quality is determined by all of the people in a conversation), it did help provide a general expectation of call quality. It was also a good troubleshooting tool to help determine on which side the connection trouble existed.

Figure 5: Gizmo call quality indicator

Skype's call quality diagnostics are not as obvious as Gizmo's and are accessed by holding the mouse pointer over the called party's icon / picture while a call is in progress. It sometimes takes patience, but once you find the hotspot, you'll be rewarded with all sorts of geeky call information as shown in Figure 6.

Figure 6: Skype call quality pop-up
(Click image to enlarge)