The HT813 is an analog telephone adapter that includes 1 analog telephone FXS port and 1 PSTN line FXO port.

For more flexibility, the FXS port forwards the VoIP service to an analog device. Users can convert their analog technology to VoIP with the HT813's ultra-compact size, HD audio quality, advanced VoIP features, top-of-the-line protection, and multiple auto-insurance options.
These advanced features allow service providers to provide high-quality IP service to customers who upgrade to VoIP