The Grandstream BT200 offers a family of affordable, next generation SIP phones that features excellent audio quality and rich telephony features. The Grandstream BT200 also supports popular voice codecs and is designed to be fully interoperable with 3rd party SIP providers.Grandstream Budgetone 200 Features:Support SIP, TCP/UDP/IP, RTP/RTCP, HTTP, ICMP, DNS, DHCP, NTP, TFTP protocolsSupport NAT traversal via STUN & symmetric RTPInteroperable with various 3rd party SIP end user device, Proxy/Registrar/Server, and gateway productsAdvanced Digital Signal Processing (DSP) to ensure superb hi-fidelity audio qualityAdvanced and patent pending adaptive jitter buffer control, packet delay & loss concealment technologySupport popular vocoders including G.723.1 (5.3K/6.3K), G.729A/B, G.711 (a-law and u-law), G.726, G.728, and wide-band G.722 (Model 102D). Dynamic negotiation of codec and voice payload lengthSupport standard voice features such as Caller ID Display or Block, Call Waiting, Hold, TransfForward, FLASH, in-band and out-of-band DTMF (RFC2833), Dial Plans, off-hook auto dial, configurable emergency dialing (e.g., 911), early dial, click-to-dialSupport 3-way conferencing (Model 102D), full duplex hands-fredomain acoustic echo cancellation (pending), redial, call log, volume control, voice mail with indicator, downloadable ring tone (pending)Support Silence Suppression, VAD (Voice Activity Detection), CNG (Comfort Noise Generation), Line Echo Cancellation (G.168), and AGC (Automatic Gain Control)Support DIGEST authentication and encryption using MD5 and MD5-sess.Provide easy configuration thru manual operation (phone keypad and Web interface) or personalized automated provisioning via central configuration file for mass deployment.Support for Layer 2 (802.1Q VLAN, 802.1p) and Layer 3 QoS (ToS, DiffServ, MPLS)NAT-friendly remote software upgrade capability (via tftp) even from behind firewalls/NATs.