AudioCodes Mediant 600 - FXS;FXO Coefficient Types; FXO Operating Modes; FXO Operations for IP-To-Tel Calls

SIP User's Manual 332 Document #: LTRT-83310
Mediant 600 & Mediant 1000
18.6.12 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 166).
These Coefficient 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
18.6.13 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 332)

For Tel-to-IP calls (see 'FXO Operations for Tel-to-IP Calls' on page 335)

Call termination on FXO devices (see 'Call Termination on FXO Devices' on page 337)
18.6.13.1 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 332)
• Waiting for dial tone (see 'Two-Stage Dialing' on page 334)
• Time to wait before dialing
• Answer supervision

Two-stage dialing (see 'Two-Stage Dialing' on page 334)

Dialing time: DID wink (see 'DID Wink' on page 334)
18.6.13.1.1 One-Stage Dialing
One-stage dialing is when the FXO device receives an IP-to-Tel call, off-hooks the PBX
line connected to the telephone, and then immediately dials the destination telephone