The Grandstream HT503 is an analogue telephone adapter featuring 1 analogue telephone FXS port and 1 PSTN line FXO port. The integration of a FXO and FXS port enables remote call origination and termination to and from the PSTN line, known as “hop-on and hop-off” calling. The 1 FXS port allows for extension of a VoIP service to 1 analogue phone. In addition to being SIP compliant, the Grandstream HT503 features support for up to 2 SIP account profiles, excellent voice quality and advanced telephony features.

Network integration between PSTN and POTS has never been so easy. The HT503 is a hybrid analog telephone adapter and VoIP router that enables the user to create an easily integrated hybrid solution with backup lifeline support.


  •   1 FXS analog telephone ports (RJ11), 1 PSTN line FXO port, dual 10/100 Mbps ports with integrated NAT router
  •    Advanced telephony features include caller ID, call waiting
  •    3-way voice conference, transfer, forward, do not disturb, message indicator, multi-language voice prompts, T.38 fax, flexible dial plan and more
  •    Supports up to 2 SIP accounts
  •    Status LED for power, telephone and network ports, and message waiting indication


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