A 21-year 5.4% semiannual coupon bond with a par value of $1,000 may be called in 6 years at a call price of $1,025. The bond sells for $1,051.64. (Assume that the bond has just been issued.)

What is the bond's yield to call? Suppose that, in the hope to revive the economy, the Federal Reserve decided to lower the interest rate to a level below 0%, What would be the impact on the likelihood of the callable bonds getting called in the U.S.? Explain your reasons step by step.