Specifications: Handytone analog telephone adapters/iad series offer a comprehensive line of voip access devices that feature full compliance with industry standards, superb audio quality, rich functionalities, high level of integration, compactness, and great affordability. Handytone series comparison table Features ht-286 ht-386 ht-486 ht-488 ht-496 Ethernet ports 1 1 2 2 2 Dhcp/nat/router no no yes yes yes Fxs port 1 2 1 1 2 Fxo port no no no yes no Pstn pass-through port no yes yes yes no Remote configuration tftp/http tftp/http tftp/http tftp/http tftp/http * fxo port allows local and remote pstn-to-voip call origination and voip-to-pstn call termination, automated call routing through pstn, and power fail-over. Pstn pass-through allows local pstn line service for income/outbound call and failover.