Have a strange request from customer, they want to know what the decibel level in the handset in 18D phone? The customer is going to place a headset on these phones and wants to know what the decibel level is? We told him and gave him the catalog sheet showing the headsets available for Partner phones, but they want to know the Db level. Any suggestions? I have look at Avaya support for white paper but could find any information.