FXO (Foreign Exchange Office) Telephony Trunk Interface Module

The FXO (Foreign Exchange Office) telephony trunk interface module (P/N XR0025) is used to connect analog telephone trunks (and in some cases legacy PBX) to the Asterisk PBX.
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Each FXO telephony trunk interface module has 8 ports for 8 analog telephone trunks. The Astribank unit is cable of carrying up to 4 FXO modules supporting up to 32 analog trunks. FXO also supports fax, however, when using FXO and ISDN (BRI, PRI or R2 digital telephony) on the same system, the fax line must be connected to ISDN.

XR0025 Technical Specifications


  • 8 FXO ports for 8 analog telephone lines
  • 80 dB dynamic range for transmitting and receiving
  • 3 micro-Ampere on-hook current
  • Programmable digital hybrid for near-end echo reduction
  • Caller ID detection
  • Pulse dialing support
  • Fax support
  • Available in combined units with other types of ports (see the “Astribank Telephony Interfaces Configurations” section on the Astribank page)

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