Callcentric offers the cheapest phone number if you aren’t concerned over the first 3 digits. If the first 3 digits is important to you, then there are other cheaper options, but my experience is best with Callcentric, even if they charge more for their numbers outside of the Dollar Unlimited options. Callcentric also offers pretty good technical support even if it is via a support ticket system which I am not happy about. Still, Callcentric works pretty well, and that is the important thing, right?