SIP User's Manual 430 Document #: LTRT-12804
Mediant 800 MSBG
8.3.5 FXS and FXO Capabilities
8.3.5.1 FXS/FXO Coefficient Types
The FXS Coefficient and FXO Coefficient types used by the device can be one of the
following:
US line type of 600 ohm AC impedance and 40 V RMS ringing voltage for REN = 2
European standard (TBR21)
These types can be selected using the ini file parameters FXSCountryCoefficients (for
FXS) and CountryCoefficients (for FXO), or using the Web interface (see ''Configuring
Analog Settings'' on page 108).
These Co
efficient types are used to increase return loss and trans-hybrid loss performance
for two telephony line type interfaces (US or European). This adaptation is performed by
modifying the telephony interface characteristics. This means, for example, that changing
impedance matching or hybrid balance doesn't require hardware modifications, so that a
single device is able to meet requirements for different markets. The digital design of the
filters and gain stages also ensures high reliability, no drifts (over temperature or time) and
simple variations between different line types.
The FXS Coefficient types provide best termination and transmission quality adaptation for
two FXS line type interfaces. This parameter affects the following AC and DC interface
parameters:
DC (battery) feed characteristics
AC impedance matching
Transmit gain
Receive gain
Hybrid balance
Frequency response in transmit and receive direction
Hook thresholds
Ringing generation and detection parameters
8.3.5.2 FXO Operating Modes
This section provides a description of the device's FXO operating modes:
For IP-to-Tel calls (see ''FXO Operations for IP-to-Tel Calls'' on page 430)
For Tel
-to-IP calls (see ''FXO Operations for Tel-to-IP Calls'' on page 433)
Call termi
nation on FXO devices (see ''Call Termination on FXO Devices'' on page
436)
8.3.5.2.1 FXO Operations for IP-to-Tel Calls
The FXO device provides the following operating modes for IP-to-Tel calls:
One-stage dialing (see ''One-Stage Dialing'' on page 431)
• Waiting for di
al tone (see ''Two-Stage Dialing'' on page 432)
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