The SPA2102 is a VoIP gateway and router. It is sold by Cisco

Cisco

Cisco may refer to:Companies:*Cisco Systems, a computer networking company* Certis CISCO, corporatised entity of the former Commercial and Industrial Security Corporation in Singapore...

 under the Linksys

Linksys

Linksys by Cisco, commonly known as Linksys, is a brand of home and small office networking products now produced by Cisco Systems, though once a separate company founded in 1995 before being acquired by Cisco in 2003...

 brand.

Hardware

The SPA2102 has:

• Two RJ-11 POTS (Plain Old Telephone Service) Foreign exchange station (FXS) ports.
• Two 100BaseT RJ-45 Ethernet ports.

The two Ethernet ports are to be used to act as a router between a modem and an internal network. The device can also be configured within an internal network by connecting only to the WAN Ethernet port.

Uses

The SPA2102 can be used in one of two primary ways:

• To connect an analog phone to a VoIP service provider, such as Vonage
  Vonage
  Vonage is a publicly held commercial voice over IP network and SIP company that provides telephone service via a broadband connection. The company's name is a play on their motto "Voice-Over-Net-AGE"....
  
   and Talkworx
• To connect a traditional POTS
  Plain old telephone service
  Plain old telephone service is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world....
  
  -based PBX to a VoIP service provider versus using a PSTN telephone company.

• • The two FXS ports can be connected to the same VoIP service provider, or each one to a separate provider.

External links

• SPA2102 Datasheet
• Cisco Administration Guide
• Explaining Dial Plans
• SPA2102 Installation Guide (public domain content)