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Configuring Call Transfers and Conferencing

A number of parameters needs to be configured before your Modem or Telephony Card (eg. Dialogic) can correctly transfer and conference calls.

The most important parameters are the signals which your PBX or Telephone Network uses to place calls on hold and to forward or conference calls. If you do not know what those signals are, you will probably need to ask your PBX supplier or call your Telephone Company.

On almost all systems the "hookflash"(also known as "flash") signal is used in one way or another. Hookflash is just the task of hanging up the call on-hook for a very short time and then 'picking up the handset' again. The length of the hookflash required differs from system to system - the length used by your Modem or Telephony Card will have to match that required by your PBX / Telephone Network, otherwise the transfers/conferences will not work. If the hookflash is set to short then it will not be noticed by the PBX (the caller will just hear a short click on the line) and if the hookflash is set too long then the PBX will interpret it as a receiver hanging up and will end the call.

Most modems cannot vary the length of their hookflash, and if their default length does not match the length required by your PBX / Telephone Network then you will not be able to use that modem to transfer/conference calls.

Telephony Cards allow the hookflash length to be set by the user ---ensuring that a Telephony Card can be configured to allow it to successfully perform call transfers and conferencing. This is why it is highly recommended to use a Telephony Card if your application needs to do call transfers / conferencing.


Setting Hookflash length on Dialogic cards - Approach 1 (TAPI)

Press Advanced to show the Configuration Service window:

The Hookflash time can be set in the Flash Time text box. The default value of 50 represents a hookflash time of half a second. Many systems require a value lower then that - around 100 or 200 milliseconds - requiring a value of 10 or 20 specified in the Flash Time text box respectively. The half a second long hookflash which is generated if the setting is left at 50 will on most PBXs result in the call being ended by the PBX when the hookflash is issued.

Note: Any changes made in the Dialogic's Configuration Service window will not take effect until the Dialogic System Service is restarted. If you don't know how to do this then just restart the computer.

Press the Help button on that screen to learn more about configuring your Dialogic card.

If the above does not work on your system (this usually happens on WindowsXP systems) then try using the .PRM method outlined below:


Setting Hookflash length on Dialogic cards - Approach 2(.PRM file)

Determine which parameter file is used by the Dialogic Configuration Manager and then change the hookflash length specified in the parameter file.

The release/installation notes which came with the card should inform you what Parameter File you should be specifying in the DCM - if you do not have the release notes then contact the supplier and they should be able to advise you which .PRM file to use.  

If you have not specified the parameter file explicitly in the Dialogic DCM's "ParameterFile" setting then you can determine which parameter file is being used based on what "Country" is specified. The filename of the parameter file loaded for a D/4PCI is xx_d4p.prm where "xx" is based on what country is selected. Eg: If country setting is "Australia/NZ" then the prefix is "an" and the paramter file for a D/4PCI is  an_d4p.prm
The parameter files are located in Dialogic's \DATA\ subdirectory (Usually "C:\Program Files\Dialogic\DATA").

You will need to change the line:

# PARAM 52:(DECIMAL WORD) 50 # Hook Flash/earth recall duration


PARAM 52:(DECIMAL WORD) 10 # Hook Flash/earth recall duration

ie: remove the # at the beginning and change 50 to 10. Parameter is in 10ms units, so a setting of 10 will indicate 100ms.

Then restart Dialogic service for it to read in the parameter file.

Configuring Dialogic controlled call transfers

The PBX signals are then configured using the Dialogics' s TAPI service configuration panel:

The screen above shows the basic configuration which should work for many PBX systems. You will need to consult your PBX or telephone system support staff to determine the appropriate settings for your system.

Further help on configuring the Dialogic settings can be found in the Dialogic help file.

Note: Any changes made in the Dialogic's Configuration Service window will not take effect until the Dialogic System Service is restarted. If you don't know how to do this then just restart the computer.

The examples above show configuration screens used by the Dialogic's TAPI driver. When using CT Media please consult the CT Media manuals for instructions on setting these corresponding parameters under CT Media.



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