3Com VCX V7111, User Manual, Page: 383 / 464

3Com
®
VCX V7111 VoIP Gateway User Guide
383
using the TrunkPack Downloadable Conversion utility (see Creating a Loadable Prerecorded
Tones File ).
The raw data files must be recorded with the following characteristics:
ƒ Coders: G.711 A-law, G.711 µ-law or Linear PCM
ƒ
Rate: 8 kHz
ƒ Resolution: 8-bit
ƒ Channels: mono
The generated PRT file can then be loaded to the V7111 gateway using the BootP/TFTP
utility (see
Loading the Auxiliary Files via the ini File ) or using the Embedded Web Server
(see Auxiliary Files ).
The prerecorded tones are played repeatedly. This enables you to record only part of the
tone and play it for the full duration. For example, if a tone has a cadence of 2 seconds on
and 4 seconds off, the recorded file should contain only these 6 seconds. The PRT module
repeatedly plays this cadence for the configured duration. Similarly, a continuous tone can
be played by repeating only part of it.
The maximum size of a PRT file that can be loaded to the gateway is 100 KB.
The Coefficient Configuration File
The Coeff_FXS.dat file is used to provide best termination and transmission quality
adaptation for different line types for FXS gateways. This adaptation is performed by
modifying the telephony interface characteristics (such as DC and AC impedance, feeding
current and ringing voltage).
The coeff.dat configuration file is produced specifically for each market after comprehensive
performance analysis and testing, and can be modified on request. The current file supports
US line type of 600 ohm AC impedance and40 V RMS ringing voltage for REN = 2.
To load the coeff.dat file to the V7111 gateway use the Embedded Web Server (see
Regional Settings ) or alternatively specify the FXS coeff.dat file name in the gateways ini file
(see Loading the Auxiliary Files via the ini File ).
The Coeff.dat file consists of a set of parameters for the signal processor of the loop
interface devices. This parameter set provides control of the following AC and DC interface
parameters:
ƒ DC (battery) feed characteristics
ƒ AC impedance matching
ƒ Transmit gain
ƒ Receive gain
ƒ Hybrid balance