VoiP or other cheap per minute solutions for IVR telephony


Was looking around for a few answers, but didn’t find any. Basically, I was wondering about the following:

  1. What’s the cheapest rate one can get these days with a traditional landline carrier to use for IVR systems, both inbound and outbound calling? (is there a difference between the two?) This is for intra-U.S. only.

  2. Can VoIP providers like Vonage be used with IVR systems like Asterisk? And, for VoIP, do they charge for incoming call minutes (user calls IVR) or only outgoing (if the IVR calls a user)?

I assume calls can never be free (except perhaps incoming calls?) since even with VoIP there’s the “last mile” and someone (a local carrier) has to accept the VoIP call and transfer it to a land line (digital or analog POTS).