In the Judicial Experts' Report (not BEA) ordered by the Investigating Judge there's a 4th unidentified voice on the DCVR.
It's also in BEA's report: female voice on track 1 "allo?" ... "oui" ... "allo?"
then: "bruits similaires à un combiné de l’interphone cabine qu’on essaye de raccrocher" (the english translation omits the "trying to").
Keep in mind that the airplane is in "deterrent buffet".