A bond that can be called (redeemed) because of the issuer ahead of its readiness, on particular telephone call dates, at call costs. From the call dates, the issuer gets the right, however the obligation, to purchase straight back the bonds from the relationship holders on call cost. Theoretically speaking, the bonds are not actually purchased and held by the issuer, but cancelled instantly or no longer accrue interest within initial voucher rate.
A bond that may be known as (redeemed) by the issuer prior to its maturity, on particular telephone call times, at call prices. In the telephone call times, the issuer has got the right, but not the responsibility, to get back the bonds through the bond holders at the telephone call cost. Theoretically talking, the bonds are not really bought and held because of the issuer, but cancelled instantly or no further accrue interest at the original coupon rate.