Recently I moved from MP-114 to MP-118 and got the problem. MP-118 didn't detect "the handset is lifted" during IP->Tel call. I've spent two days and found simple solution - “Enable Polarity Reversal: Disable”. (In contravention of the “Configuring Audiocodes MP-114 & MP-118 with 3CX Phone System” guide. URL: http://www.3cx.com/voip-gateways/audiocodes-mp.html ) Of course, we have lack of documentation from AudioCodes. I think they are quite lazy to make some quality docs.