The Linksys PAP2 is an analog telephony adapter (commonly referred to as ATA), which allows for the connection of one or two â€œnormalâ€ telephones to a VoIP provider using the Session Initiation Protocol (SIP) protocol. The SIP traffic is sent through the PAP2's Ethernet port. The device is one of Linksys's first entries into the Consumer / SOHO Voice over IP devices market.
The PAP2 is based on the Sipura SPA-2000 ATA design. The device is powered by an ESS Visba 3 (ES3890F) chipset. It utilizes a Realtek RTL8019AS 10BaseT Ethernet controller, which provides a 10 Mbit/s/ half duplex connection to a LAN.
The units have 2 RJ11 sockets, which allows for two "lines" (each with their own unique SIP registrar / username etc, for truly separate configuration), however in the case of the locked units, the second line may be inaccessible, unless your provider specifically sets it up (for example if you had two Vonage lines).
The original PAP2 has been discontinued. The PAP2 version 2 and the PAP2T are successors with similar capabilities. They are different enough that they have distinct firmware. The PAP2 version 2, unlike the others, runs Linux (Linksys has released source for the GPLed portions of the firmware).