Break times and meal times for hourly employees should be used for those purposes, not for work. And you should put that policy in writing.
While that may force you to juggle staffing to ensure coverage, it's worth it to avoid back pay, overtime and penalties after a lawsuit, as a recent case illustrates.
Federal law says you don't need to pay hourly workers for break time as long as they are "completely relieved of duty."
Recent case: Nurses at an Oklahoma hospital were regularly interrupted during their meal breaks to respond to patient problems and answer phones. The hospital didn't pay such hourly employees for their meal breaks, even if they performed some work during the break.
The nurses sued, claiming they were owed overtime for those working-during-break hours. A federal appeals court agreed, saying the breaks must be paid if the "degree of interruption caused [the nurses] to spend their meal periods primarily for Hillcrest's benefit." (Beasley v. Hillcrest Med. Ctr., No. 02-5121, 10th Cir., 2003)
Bottom line: Many courts have softened that standard by ruling that if employees spend their break time "predominantly" for their own benefit, you don't need to pay for that time. The more interruptions that occur, the more likely a court will find that the break was predominantly for the company's benefit, making the time payable.
That's why the smartest policy is to pay employees whenever they're called off break to perform work.