Specification :

Internet telephone service is now more accessible than before. Part of Cisco Small Business Voice Gateways and ATAs, the SPA3102 Voice Gateway allows automatic routing of local calls from mobile phones and land lines to Voice over Internet Protocol ( VoIP) service providers, and vice versa.
By first calling the local number on the SPA3102, you can reduce or eliminate long-distance charges altogether.
If power goes out or Internet service is lost, calls can be safely redirected to a traditional carrier via the standard analog interface.
Additional features of the Cisco SPA3102 include:
One RJ-11 POTS ( Plain Old Telephone Service) FXS port to connect an existing analog phone or fax machine
One PSTN FXO port to connect to a Telco or PBX circuit
Two 100BaseT RJ-45 Ethernet interfaces to connect to a home or office LAN, and an Ethernet connection to a broadband modem or router
FXS and FXO lines that can be independently configured
Secure encryption-based methods for communication, provisioning, and servicing