Redemption value
Redemption value is the price at which the issuing company may choose to repurchase a security before its maturity date.{{cite web | url=http://www.12manage.com/description_redemption_value.html | title=Redemption Value |accessdate=November 12, 2007}}
A bond is purchased "at a discount" if its redemption value exceeds its purchase price. It is purchased "at a premium" if its purchase price exceeds its redemption value. Thus, the right will only be exercised at a discount.
[https://www.sec.gov/answers/callablebonds.htm Callable or Redeemable Bonds], sec.gov