The FAA has a ‘‘one phone call’’ policy that ‘‘generally allows a certificate holder to initiate one phone call during crewmember’s rest period.’’ If the crewmember voluntarily chooses to answer this phone call, then the FAA does not view the call as disruptive and breaking the rest period. The sleep-opportunity requirements of § 117.25 do not eliminate this policy. However, the FAA cautions that a flightcrew member may have difficulty getting back to sleep after being woken up by a certificate holder’s phone call. In that situation, a flightcrew member may notify the certificate holder, pursuant to § 117.25(f), that his or her sleep opportunity has been interrupted. Thus, a certificate holder runs the risk of interrupting a flightcrew member’s sleep opportunity if the certificate holder calls a flightcrew member during the flightcrew member’s rest period.