VoIP weaknesses
As the saying goes, there's no such thing as a free lunch. While the savings offered by VoIP services make them very attractive, there are some other factors that need to be considered before jumping aboard.

The first is call quality. Because VoIP calls travel over the Internet rather than the telephone network, they have to compete with a lot of other traffic. The performance of computer networks is affected by the amount of data travelling over them, so when things are busy, delivery delays can occur. Sometimes data packets can get lost altogether as they try to find their way to their destination.

For VoIP calls, such delays and losses cause drops in call quality. Words might sound clipped or the connection may drop out for fraction of a second. In worst cases, calls are all but unintelligible. However, many of the major VoIP service providers are working to interconnect their own networks. This will help to keep call traffic away from the public Internet and so improve call quality.

You'll also need a decent broadband connection. Many VoIP providers recommend using nothing slower than a 512 kbps download/128kbps upload link. Anything below this can have an adverse effect on call quality.

Also, because you need a broadband connection to make and receive calls, you also need power. If there is a blackout, you'll lose your service. The traditional phone network has been designed to operate without main power, but this isn't the case with a VoIP service. Mind you, this power limitation also applies to cordless landlines that are popular in many Australian households.

It's also worth remembering that VoIP calls are treated like any other type of broadband usage by your ISP. Calculations vary, but as a rough guide, each 10 minutes of talking will eat up 1MB of your download quota. Anyone with a small monthly cap will need to pay close attention to their usage.