The first adapter received not working - inaudible - the seller, very responsive I have to admit, sent me a second "not tested his care." Even of failure. According to him, it is incompatible with the phone and / or headset (both working fine elsewhere). The problem is to know which materials are compatible, which is not specified anywhere. So I returned the two adapters and I expect reimbursement (more than a week already). Finally, assuming that the adapter works is a lottery in terms of models of compatible phones or headsets.