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Introduction
This article provides an overview of "best practices" when installing and configuring Dialogic Brooktrout® SR140 Fax Software (SR140) the Dialogic 1000 or 2000 Media Gateways (DMG1000 and DMG2000). This article is intended for fax independent software vendors (ISVs) who have integrated the SR140 into an application.
Background
When setting up an SR140-based application to work with a DMG1000 or DMG2000 gateway, there are certain guidelines that should be followed. One should also consider these guidelines when migrating from Dialogic Brooktrout Fax Boards which are based on time-division multiplexing (TDM) protocols. When upgrading from traditional analog fax to a Fax over IP (FoIP) solution, it is necessary to provide a sufficient level of network performance to support reliable operation. Fax transport over an IP network can be provided by T.38 fax relay or G.711 pass-through, each one having different network requirements. An overview of considerations for using T.38 versus G.711 for FoIP .
Please note that if the user is still unsure on how to utilize these parameters, the user should discuss this with its fax ISV or a Dialogic technical support representative.
SECTION 1 - SR140 OVERVIEW AND TUNING
Fax Application Considerations - Ensure the fax application software version is performing resets between all calls. Resetting channels is accomplished with the BfvLineReset API function. If an application does not reset the channel between each call, then the channel can be left in an unpredictable state from which it would not recover and which would cause issues during fax calls.
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If the site has an existing Brooktrout Fax Board - please obtain a recording from the setup. The audio file will be used by the Dialogic technical support team to understand the audio levels that are present on the line and if further adjustments might be necessary.
The fax application being used may have the capabilities to record the audio file. Please check with your fax ISV.
This article also has attached a sample application that can be used to gather the recording. The sample recording application is called voicermd.c,
, and can be used on channels 2 and 3 to record the inbound and outbound streams.View file name 4128_voicermd.zip The parameter "debug_control 1 3" would need to be added into btcall.cfg to turn on the recording feature; Dialogic technical support can assist with using this feature.
SR140 Log Collection -when troubleshooting, the following logs always needs to be gathered. It is important to collect all the various logs together. If logs are collected from different time frames, they will not assist in isolating the issue being examined.
Debug log – channel information needs to be included in the log, e.g., "[41,2]", "[41,3]", … etc. If a debug log has only Admin channel information, i.e. "[41,1]", then it would not be of value in isolating an issue.
ECC log - make sure to use a full path name for the "trace_file" parameter in callctrl.cfg and also make sure that the Bostsrv service points to the same btcall as the one that the application uses when it calls BfvLineReset. This will make sure that all of the call control information will appear in the ECC log, most importantly the SIP messages.
Wireshark - traces should be gathered from the SR140 and DMG1000 or DMG2000 points. This will help in analyzing the call flow and information flowing through the network.
SECTION 2 - DMG1000/DMG2000 Usage Overview
DMG Software Versions – it is recommended that DMG SU version level be SU9 or later. SU9 and later have defaults that provide better performance for FoIP configurations.
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