The HT813 is an analog telephone adapter that features 1 analog telephone FXS port and 1 PSTN line FXO port in order to offer backup lifeline support using 

a PSTN line. The integration of a FXO and FXS port enables this hybrid ATA to support remote calling to and from the PSTN line. For added flexibility, the FXS 

port extends VoIP service to one analog device. Users can convert their analog technology to VoIP thanks to the HT813’s ultra-compact size, HD voice quality, 

advanced VoIP functionality, high-end security protection and multiple auto provisioning options. These advanced features also allow service providers to 

offer high quality IP service to customers looking to upgrade to VoIP