This statement caught my eye.

"... rural customers “have experienced problems with their phone
service, ranging from situations in which the calling party hears ringing but the called party hears
nothing (or there is an unusually long call set-up), the called party’s phone rings but the party
hears dead air when the call is answered, or there is extremely poor quality on answerable
calls.”

http://transition.fcc.gov/Daily_Rele...1/ddtoday.html

This letter was referring to rural phone carriers, but noted these problems were most likely due to "... to the interworking of TDM-and IP-based technologies in today’s current generation network and are under the control of originating carriers and intermediate providers within the call path."