Grandstream HT503 Maximize

Grandstream HT503

HandyTone HT503 is the next generation of powerful, affordable, high quality and manageable IP telephony ATA/IAD

VoIP SIP HT503 ATA/Router with 1 x FXS, 1 x FXO, 1 x LAN, 1 x WAN

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The HandyTone 503 is the next generation of powerful, affordable, high quality and manageable IP telephony ATA/IAD for residential users and road-warriors. Its compact size, excellent voice quality, packed feature functionality and best-in-class price-performance point enable consumers to maximize the power of IP voice and data connectivity.  The HandyTone 503 is based on SIP standard and interoperable with most 3rd party SIP compliant devices and software. It features 1 FXS telephone port, 1 FXO PSTN line port, dual 10M/100Mbps network ports, port status and message waiting LED, and a base stand for vertical positioning.


  • 1 FXS telephone port (RJ11), 1 FXO PSTN line port (RJ11) with power-outage life line support,
  • Up to 2 SIP account profiles, SIP over TCP/TLS, SRTP
  • Dual 10/100 Mbps network ports (RJ45) with integrated high performance NAT router
  • Status LED for power, telephone, PSTN line, network, and message waiting indication
  • Advanced telephony features
    • caller ID from both IP and PSTN,
    • call waiting, 3-way conference with IP and/or PSTN,
    • remote call origination and termination from/to PSTN,
    • hop-on and hop-off calling,
    • transfer to OR forward to IP or PSTN,
    • do not disturb,
    • message waiting indication,
    • multi-language voice prompts,
    • flexible dial plan, direct IP calling
  • Comprehensive voice codecs
  • Secure and automated provisioning using HTTP/HTTPS/Telnet/TFTP
  • Symmetric and asymmetric voice codec/RTP in any call sessions
  • T.38 Fax
  • SIP over TCP/TLS


  • IP connectivity for any phone and fax
  • Hop-on/Hop-off calling
  • Web management for easy configuration and installation
  • Offers traditional and advanced telephony features
  • Portable and compact for use at home or on the road
  • Ports FXS, WAN, FXO, LAN
  • Provisioning Http, Tftp, Https
  • Codecs G.729a, G.711 (alaw), G.729ab, G.711 (ulaw)
  • Networking VLAN 802.1Q, QOS
  • Other VAD
Phil M

Very good VOIP gateway

I bought the HT503 as a gateway between my company's VOIP system and PSTN line.
This device works as expected and it has many options. Also, it is easy to configure.
It does also do automatic upgrade of it's firmware via internet, so I always know that I have the latest firmware.
The main thing is that there is no busy tone problem with FXO port and that's very nice for me.
I like HandyTone products from Grandstream.
Nice and simple!

    Troy A

    My first adapter/My great adapter

    Works good with my VoIP Service.
    Got it up and running with Asterisk as an incoming outgoing trunk for a POTS line.
    Good product, this unit doesn't have any echo issues at all.
    I would recommend this product to a friend.

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