FO MISUNDERSTOOD CLRNC WHILE CAPT WAS OFF FREQ AND THEY MISSED AN ALT XING RESTR.

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I XFERRED CTL OF BOTH THE ACFT AND ATC RADIOS TO THE FO SO I COULD CALL COMPANY. I WAS TRYING TO DISCUSS ALTERNATIVE DESTS AS OUR DEST WX WAS DROPPING. I ASKED THE FO TO GET US A HOLD OVER PLANO INTXN. PHONE PATCH WAS COMING IN BROKEN; SO I TURNED THE #1 RADIO (ATC) DOWN. I WATCHED THE FO ENTER THE HOLD INTO THE FMS. ONCE I WAS THROUGH WITH COMPANY; I TURNED THE #1 RADIO BACK UP AND TOOK CTL OF THE ACFT AGAIN. FO BRIEFED ME THAT WE HAD BEEN GIVEN A HOLD OVER PLANO INTXN. APCHING PLANO; ATC ADVISED US THAT WE WERE SUPPOSED TO CROSS PLANO AT 14000 FT. I IMMEDIATELY QUERIED THE FO AND SHE SAID THAT SHE UNDERSTOOD OUR CLRNC TO BE FOR FL240. UPON FURTHER PRODDING; SHE EXPLAINED THAT WE HAD BEEN CLRED TO CROSS 40 DME SE OF ORD VOR AT 14000 FT. SUBSEQUENTLY; WE HAD BEEN CLRED TO PLANO INTXN FOR THE HOLD. SHE UNDERSTOOD THAT TO MEAN OUR PREVIOUS XING RESTR WAS NO LONGER VALID. I REALIZE NOW THAT I DID NOT PRIORITIZE PROPERLY. AS THE CAPT; IT IS MY RESPONSIBILITY TO MAKE SURE THE FLT OPERATES SAFELY AND LEGALLY. I SHOULD HAVE TOLD COMPANY TO STAND BY WHILE I ASSIGNED THE FO IN OBTAINING A PROPER HOLDING CLRNC. SECONDLY; I SHOULD NOT HAVE TURNED DOWN THE #1 RADIO; NO MATTER WHAT DIFFICULTY I WAS HAVING HEARING THE #2 RADIO. IN THE FUTURE; I WILL TRY TO MANAGE MY FLT SO AS TO AVOID SUCH A HIGH WORKLOAD.