Call Protection

No, this doesn't prevent your ex from calling you at 3 AM. It has to do with bond purchases.

Some bonds include a provision that makes them "callable." This clause allows the issuer to buy them back on certain pre-specified dates before the maturity date. Issuers put this in place as a protection against falling interest rates. Nobody wants to get stuck paying out a 7% bond when the prevailing rate has fallen to 4%. In this scenario, a callable bond could be repurchased by the issuer and then new bonds sold at the lower rate.

For purchasers, callable bonds are less valuable because you don't know you'll get the full interest rate you've been promised. They could get called in. Usually this means that the interest rate on these bonds has to be a little higher than the going rate, in order to compensate investors for the added call risk.

There's also call protection.

Call protection lives the fine print in the paperwork. When you buy a bond, this language protects the buyer from having the bond called in...for a period of time. A typical call protection bars issuers from calling in a bond during a time period soon after purchase. For instance, the issuer might have to wait at least five years before calling its bonds and issuing cheaper bonds.