Broadband phones work using the internet over broadband (or faster connections if you have one). They are often called VoIP - Voice over Internet services.  (You may also find references to SIP - Session Initiation Protocol.)  But it all means the same thing - you can use your broadband connection to run not only your internet but also a phone service! 

• no need for another 'telephone line'
• number is truely portable
• service can be diverted through a secure webpage when you choose