IEEE 802.1p , IEEE 802.1Q (VLAN) , Type of Service (ToS). Acoustic echo cancellation (AEC) , Adaptive jitter buffer (AJB) , Automatic gain control (AGC) , Comfort noise generation (CNG) , HD Voice , Packet loss concealment (PLC) , Voice activity detection (VAD). Visual ringer light , Voice message waiting indicator. Key Expansion Module Max Qty. The item "NEW Yealink Optima HD Touchscreen Skype VoIP IP Gigabit Phone P/N SIP-T48S" is in sale since Tuesday, July 18, 2017.This item is in the category "Computers/Tablets & Networking\Home Networking & Connectivity\VoIP Home Phones". The seller is "bectechglobal" and is located in Irvine, California. This item can be shipped worldwide.