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PRODUCT OVERVIEW
The HT503 is an affordable, high-quality, integrated IP telephony solution for both the residential
customers and the ‘road-warriors’ who need advanced call features between traditional PSTN network
and IP network. The HT503 enables IP connectivity for any phone or fax using the FXS port and a web-
based GUI for easy configuration and installation. It functions as a true FXO gateway that enables remote
call origination and termination from/to PSTN and supports the feature of “hop-on/hop-off” using the
programmable FXO port.
The HT503 features 2 SIP account profiles and supports advanced telephony features including caller ID,
call waiting, call transfer, 3-way conferencing (with either IP or PSTN calls), and multi-language voice
prompts. From a technical standpoint, the HT503 offers a power-outage survivable life line and internet-
disconnect survivable fail-over-to-PSTN support, dual 10/100Mbps Ethernet ports with integrated high-
performance NAT router, a flexible dial plan and a broad range of popular voice codecs.
T
ABLE 2: HT503 TECHNICAL SPECIFICATIONS
Interfaces
1 FXS telephone port (RJ11, 1 FXO PSTN line port (RJ11) with lifeline support
Two (2) 10M/100 Mbps ports (RJ45) with integrated Nat router
Protocol Support
TCP/UDP/IP, RTP/RTCP, HTTP/HTTPS, ARP/RARP, ICMP, DNS, DHCP, NTP, TFTP,
PPPoE, STUN & TELNET protocols
LED Indicators
Power, WAN, LAN, PHONE, and LINE
RESET Button
Factory Reset Button
Device Management
Web interface or via secure (AES encrypted) central configuration file for mass
deployment
Support device configuration via built-in IVR, Web browser or central configuration file
through TFTP or HTTP
Support Layer 2 (802.1Q, VLAN, 802.1p) and Layer 3 QoS (ToS, DiffServ, MPLS)
Auto/manual provisioning system
NAT-friendly remote software upgrade (via TFTP/HTTP) for deployed devices including
behind firewall/NAT
Syslog support
DHCP Server/Client
Yes
Audio Features
Advanced Digital Signal Processing (DSP)
Dynamic negotiation of codec and voice payload length
Support for G.723.1A, G.729A/B/E, G.711, G.726-40/24/16, iLBC, T.38 codecs
In-band and out-of-band DTMF ((in audio, RFC2833, SIP INFO)
Silence Suppression, VAD (voice activity detection), CNG (comfort noise generation),
ANG (automatic gain control)
Adaptive jitter buffer control
Packet delay & loss concealment (PLC) & G.168 compliant Line Echo Cancellation
Support volume amplification
Support configurable Call Progress Tones
Call Handling Features
Caller ID display or block, Call waiting caller ID, Call waiting/flash, Call transfer, hold,
call forward, do not disturb, 3-way conferencing
Network and
Provisioning
Manual or dynamic host configuration protocol (DHCP) network setup; RTP and NAT
support traversal via STUN
Fax over IP
T.38 compliant Group 3 Fax Relay up to 14.4kpbs and auto-switch to G.711 for Fax
Pass-through (pending), Fax Data pump V.17, V.19, V.27ter, V.29 for T.38 fax relay
Security
DIGEST authentication and encryption using MD5 and MD5-sess
Physical Design
Stylish and compact design; small universal power supply, ideal for travel
Grandstream Networks, Inc. HT503 User Manual Page 7 of 35
Firmware 1.0.0.6 Last Updated: 6/2007