Analog Voice Interfaces
Cisco routers utilize analog voice interfaces to interface either directly with telephone
handsets, or to connect to legacy PBX or the PSTN. Because analog technology
is considered a much older and more stable technology, these interfaces
are standardized.There are currently three types of analog interfaces supported by
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New World Technologies • Chapter 2 51
Cisco routers: Foreign Exchange Station (FXS), Foreign Exchange Office (FXO),
and ear-and-mouth, sometimes known as earth and magneto (E&M). Let’s discuss
these interfaces in more detail.