6 FXS (Foreign Exchange Station), 2 FXO (Foreign Exchange Office) / IO Telephony Line Interface Module

The FXS telephony line interface is used to connect analog telephones (and in some cases legacy PBX) to the Asterisk PBX. Each FXS telephony line interface module (XR0024 or XR0045) has 8 FXS ports, which means it can drive up to 8 different analog extensions.
Product Datasheet


this module has reached end-of-life and is no longer available

The Astribank unit can support up to 4 FXS modules, reaching up to 32 analog extensions. Many Astribank units may be used on the same server to easily create a system with hundreds of analog extensions.

The first (left-most) FXS telephony line interface module in each Astribank unit may be XR0045 (8 FXS + I/O option). In this specific card, in addition to the FXS ports there are also two RJ45 connectors featuring 4 input and 2 output ports. These ports can be used to activate/deactivate peripheral devices.

XR0035 Technical Specifications


  • 8 analog extensions
  • 5 REN ringing generator
  • Programmable AC impedance
  • Up to 6,000 feet line length (1 REN) – 3 REN for 4,000 feet line
  • Constant current
  • Caller ID support
  • MWI (Message Waiting Indicator) support for analog phones
  • I/O (Input/Output ports)
  • Available in combined units with other types of ports (see the “Astribank Telephony Interfaces Configurations” section on the Astribank page)

Technical Documentation

FXS+FXO module XR0035 data sheet