VoIP Telephone Service
In New Zealand many companies are offering a range of VoIP services that replace a standard telephone line service including the ability to keep existing phone numbers.
Replace Your Standard Phone Line
Generally these services use either special IP telephones or an analogue telephone adaptor (for connecting ordinary telephones), which plug in to a broadband Internet connection or dedicated data service. There is also the option to use a Softphone (which is a software application) but this does require a computer or computing device for making phone calls.
WiFi Phones
If WiFi is being used for local networking then it is possible to use a WiFi IP-phone. WiFi IP-phones look similar to a cordless phone but instead work over wireless computer networks. Softphones can also be used with WiFi, there are softphones available for many handheld devices, such as the iPod Touch, Smart Phones or PDAs.