B767 FLC ON DSCNT REQUESTED TO CONTACT ATC ON SPECIFIC VHF FREQ.

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DURING ROUTINE ARR FROM DENVER INTO ST LOUIS WE WERE ASKED TO LEAVE FL410 EARLY TO ACCOMMODATE CTR XING TFC. ATC ASKED IF WE WOULD HAVE AN OPERATIONAL PROB DSNDING TO FL290 BY 115 MI W OF UIN. WE SAID NO PROB AND LEFT FL410 AS DIRECTED. AFTER LEVELING AT FL290 WE RECEIVED AN ACARS MESSAGE WITH A REQUEST TO CALL A SPECIFIC VHF FREQ. I ASKED THE CURRENT CTLR IF HE RECOGNIZED THE FREQ AND HE SAID IT BELONGED TO THE CTLR ABOVE HIS SECTOR. I ASKED HIM TO INVESTIGATE AND AFTER A MIN OR SO HE CAME BACK SAYING 'NO PROB.' THE OVERLYING SECTOR CTLR HAD THOUGHT HE HAD LOST COM WITH US. THE REMAINDER OF THE ARR WAS NORMAL; BUT I HAD THE UNEASY FEELING THAT WE HAD BEEN LOST BY ATC DURING THE HDOF AND I WANTED TO BE SURE WE WERE ON RECORD AS HAVING COMPLIED 'AS CLRED.' ATC AND I HAD A FRIENDLY DISCUSSION REGARDING THE XING AIRSPACE PROBS INTO ST LOUIS AND POSSIBLE SOLUTIONS SUCH AS FILING A MORE SOUTHERLY ARR DURING THE LATE AFTERNOON HRS. AS I STATED; I DO NOT BELIEVE ANY PROB OCCURRED DURING THIS FLT BUT I'M UNCERTAIN WHAT TRANSPIRED BTWN ATC SECTORS.