Configuring Call Transfers and Conferencing

VoiceGuide can do call transfers and conferencing in a number of different ways. Most common type of transfer is called a "hookflash transfer" - this method is used by most PBXs when analog lines are used. To do this transfer you'd usually just press the 'flash' button, then dial the extension to which the call is to be transferred and then just hang up.

There are however many different types of phone systems out there and many of them have their own peculiar ways of doing things. Some systems will require you to wait till the destination extension answers the call, and some systems will require you to wait only till the destination extension is ringing before hanging up. Some systems will allow you to hangup straight away. Some systems will not allow transfers but will allow 3-way conferences only. Some systems do not support call transfers at all and in such cases you'll need to make a call on another line and have VoiceGuide connect the incoming and outgoing calls together internally to route the call to a new number. The Help file's section on the Call Transfer module lists all the different ways in which VoiceGuide can do call transfers.

Before trying to get VoiceGuide to do the transfers it's best to first establish exactly how transfers can be made on your system. Note down step by step what needs to be done and what buttons need to be pressed on your system to make the transfer happen if you just use a telephone handset yourself. Once this is all established you can then go ahead and configure VoiceGuide to do exactly the same things to effect a transfer.

VoiceGuide comes with pre-programmed settings for signals which your PBX or Telephone Network uses to place calls on hold and to forward or conference calls which work for most PBXs, but your PBX / Telephone Network may require different settings. 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 PBX control strings

In VoiceGuide Script Designer click on the Edit menu and select PBX Command Strings.

The signals sent to your PBX or Telephone Network can be configured here. VoiceGuide will generate the specified signals to command the PBX / Telephone Network to perform call transfers and conferences.

The "!" character represents a hookflash.

The screen capture above shows a typical configuration which should work for many systems. You should confirm that these settings are OK with your PBX supplier or your Telephone Company, and change them if your PBX supplier or your Telephone Company indicates that they should be changed.

Note:After changing the PBX strings you will need to restart VoiceGuide before these new settings will take effect.

Setting Hookflash Length on Dialogic cards

How the hookflash length is set will depend on which version of VoiceGuide you are using.

If using VoiceGuide v7 or v6 then the hookflash length is set by editing the Config.xml file.

If using VoiceGuide v5 (TAPI) then the hookflash length is set using the TSP Configuration screens, or the .PRM file.

All 3 methods are explained in more detail below:

Setting Hookflash length on Dialogic cards - v7 and v6

A setting of 10 means 100ms. The setting is in 10ms units.
 

Setting Hookflash length on Dialogic cards - v5 (TAPI)

Win98/NT: Open Control Panel’s Telephony applet, select the Telephony Drivers tab, select the Dialogic Service Provider and the press Configure.

Win2000/XP: Open Control Panel’s “Phone and Modem Options” applet, select the Advanced tab, select the Dialogic Service Provider and then click Configure.

A Dialogic TSP Configuration window should appear:

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 150 milliseconds - requiring a value of 10 or 15 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. Some systems in USA use a 500ms hookflash.

If you do not know the precise value of the hokflash length required by your system then just experiment with various values and see how they work of you, and keep in mind the two rules below:

A. If the caller gets cut off, but the number where the call is transferred to rings OK, then flash time is too long. A long flash time is trated by the PBX as a hang-up and caller just gets cut off.

B. If the caller hears a click and then hears the DTMF that should be used to dial the number (and hence the number where the call is being transferred to doesn't ring), then the flash time is too short. This is because a hookflash which is too short will just not be noticed by the PBX and the PBX will not put the original caller on hold.

Seeing how the various hookflash lengths work on your system should allow you to quickly work out what length hookflash your system requires.

Press the Help button on the Configuration Service window to learn more about configuring your Dialogic card.

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.

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

Alternative way of setting Hookflash length on Dialogic cards - .PRM file

Setting Dialogic extension answer timeout (TAPI)

Sometimes the Dialogic card will not be able to detect if the extension to which the announced transfer is directed has answered the call if the call is answered quickly - this results in a long delay before Dialogic informs VoiceGuide that the call was answered. To decrease this time when using v5 of VoiceGuide select the "Call Parameters" tab then change the Configuration to “Custom” and edit the "Ringback Timeout" text field.
The default setting is 700 - which results in a seven second delay. The recommended value is 300 (three seconds).

Configuring Dialogic controlled call transfers (TAPI)

As mentioned before it is recommended that VoiceGuide retain control of call transfers/conferencing and be in change of generating the different signals required. You can however set VoiceGuide to use Dialogic cards TAPI drives to perform the transfers as well.

To select Dialogic TAPI drivers to perform the transfers you will need to edit the VG.INI file, setting the TransferControl_TelBoards parameter to “TAPI”. Eg:

[PBX]
TransferControl_TelBoards=TAPI

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 and hence are available to v5 of VoiceGuide only. VoiceGuide v6 and v7 allows (though Config.xml and ConfigLine.xml files) better control then the options provided through the Dialogic TSP configurations.