1) Call Hold allows you to handle VOIP and PSTN at the same time 2) The standby mode is on PSTN channel (It is necessary for emergency calls such as 911) 3) Call Alert for PSTN incoming call when you are on a Skype call. 4) Auto reply with an instant message when you are unavailable USB Gateway(skype) Features: ?Upgrade your DECT Phone or regular phone to a PSTN/VOIP Dual mode phone. ?Seamlessly integrated with Skype, VoipBuster, VoipStunt, VoipCheap, VoipDiscount, Internetcalls, NetAppel, and SparVoip, etc. ?The standby mode is on PSTN channel (It is necessary for emergency calls such as 911) ?Call Alert for PSTN incoming call when you are on a Skype call. ?Call Hold allows you to handle VOIP and PSTN at the same time ?Speed-dial up to 99 contacts ?FSK Caller ID ?Auto reply with an instant message when you are unavailable ?Intelligent Router for SkypeOut calls ?Live update the driver automatically. Specifications: ?Telephone Interface: One FXS port, one PSTN port for pass-thru ?LED: Power Indicator $ Voip Indicator ?Voltage: 4~5.25V ?Operating Humidity: 5~95% RH ?Operating Temperature: 0~40 ?Product side:14.6*12.3*3.5(mm) product weight:0.26KG