In an effort to combat call completion & call quality problems that stem from telecommunication providers who utilize inexpensive/inferior networks to transport long distance calls, a practice known as Least Cost Routing, the Federal Communications Commissions has provided rural telephone subscribers with a mechanism to report issues regarding incoming long distance calls. Please review this link and take the recommended actions if you are experiencing incoming call completion or quality problems.
http://www.fcc.gov/encyclopedia/problems-long-distance-or-wireless-calling-rural-areas