Vonage

[Robert La Ferla]

BroadVoice (a local company in Chelmsford) offers the best value ($25  
unlimited local, regional, state and to most countries in the  
world.)  They have had pretty bad customer service in the past but it  
seems to be improving.  I was ready to dump them but the price was  
hard to beat and the service hasn't been that bad.  YMMV.  They also  
support Asterisk.

http://www.broadvoice.com