...
Linksys makes a popular line of ATA devices (Analog Terminal Adapters) which allow connection of traditional analog phones to a SIP network. Two of these devices, the SPA2102 and SPA3102 are directly supported by Sipx, and appear on the device menu as ata2101 and ata3102 respectively.
These devices can be used for a variety of purposes, such as to add a special-purpose analog phone to a SIP system, to implement an external gateway to analog phone lines for backup (SPA3102 only, see Configuring Linksys Sipura FXS Gateways ), or, in residential-type applications to connect a set of analog phone jacks to a SIP service.
...