SendModemCommands Variable

Use the SendModemCommands variable to send specific commands directly to the modem. Some situations that require the use of SendModemCommands are as follows:

• Hook-flash call transfers with a voice modem.
• Performing numeric pages on outbound calls.
• Limited-time three-way calling.

In order to use call transfer features, you must have a phone line, PBX, or phone system that supports call transfers. Active Call Center will use the modem to activate the call transfers features already provided on your phone line. The same applies to three-way calling.

To use the SendModemCommands variable, set the value of the variable to the commands to send to the modem. These commands are usually based on the "AT" command set - refer to your modem's manual for detailed information.

By default, Active Call Center will disconnect the call immediately after the modem commands have been sent. If a delay is required before disconnecting the call, set the SendModemCommandsHangupDelay variable to the number of milliseconds of delay desired. For an example, refer to the section below on three-way calling.

Since SendModemCommands is processed after the macro has executed there is no need to worry about the macro not executing in its entirety (in fact, barring errors macros will always completely execute once they are started).

Every voice modem seems to have a slightly different way to send pages or perform call transfers - experiment with the options provided to find one that works with your modem.

Examples of Numeric Pages

One command that may work to do a numeric page to 555-1212 is:

SendModemCommands = _
"AT#VBT=1#VSR=7200#VTS=5,5,5,1,2,1,2"

Notice the phone number is the last part of the command with the digits of the number separated by commas.

Other commands that may work to send a simple numeric pages to 555-1212:

• SendModemCommands = "ATE0X3DT5551212"
• SendModemCommands = "AT&F0E0X3DT5551212"
• SendModemCommands = "AT&F0X3DT5551212"

For another technique to perform numeric paging, refer to the section on the PlayTouchTones Variable.

Examples of Hook-Flash Call Transfers

A hook flash is initiated by including an exclamation point in the dial string. One way to use SendModemCommands to do a hook flash call transfer to 555-1212 might be as follows:

SendModemCommands = _
"AT#VBT=1#VSR=7200#VTS=!,[0,0,20],5,5,5,1,2,1,2"

As in the numeric page example, the number is again at the end of the string. The other items in and around the phone number are as follows:

• The first ! initiates a hook flash.
• The next group [0,0,20] is 2 seconds of silence, this allows the hook flash to result in a dial tone. If two seconds is too much, change the time to 1 second by making the group [0,0,10] instead, or remove the group altogether.
• The 5,5,5,1,2,1,2 is the actual phone number that the call will transfer to.

Other commands that might also work for hook-flash transfers are as follows:

• SendModemCommands = "ATE0X3DT!,,5551212"
• SendModemCommands = "AT&F0E0X3DT!,,5551212"
• SendModemCommands = "AT&F0X3DT!,,5551212"

Three-Way or Conference Calling

We do not recommend three-way or conference calling with the SendModemCommands variables. However, several users have pointed out that there is a legitimate need for such an option even if it only works with severe limitations.

Effectively making three-way calls with modems is nearly impossible because voice modems can't tell when the two parties have left the call. After the call has ended, the modem may remain in a state that effectively ties up the phone line for an indefinite period of time.

Therefore, any method of making three-way calls must guarantee that the call will be disconnected at some point. We have found the only reliable method to guarantee that the call gets disconnected is to introduce a fixed length time delay using the SendModemCommandsHangupDelay variable. This forces a conference call to last only a specific amount of time before disconnecting. Active Call Center does not offer and more than likely will not offer a way around this limitation.

Again, we do not recommend three-way calling, but daring users can implement it approximately as follows:

' Send the three-way dialing commands
SendModemCommands = _
"AT#VBT=1#VSR=7200#VTS=!,[0,0,20],5,5,5,1,2,1,2,[0,0,20],!"
' Force the call to last 3 minutes.
SendModemCommandsHangupDelay = "180000"

Note that the dial commands for a three-way call require two hook-flashes (exclamation points): one at the beginning to start the three-way call and one at the end to connect the three parties. For a discussion of hook-flash style modem commands that may work for your modem, refer to the section above on hook-flash transfers.

It may also be possible to implement conference calling with the PlayTouchTones variable.

"AT" Modem Command Basics

The "AT" command set is a standard set of commands used by many voice modems that have Rockwell or compatible chipsets. All commands in the "AT" command set are prefixed with "AT".

The "AT" is followed by any of a number of different command codes. Some useful codes to know are:

• &F0 resets the modem to its original configuration.
• E0, E1 codes which control whether or not commands are repeated (echoed) back by the modem. E0 = disable command echo, E1 = enable command echo.
• D is used for a dial command. With a D, the T command suffix signifies tone dialing, P for pulse dialing, a W indicates to wait for a dial tone. Dial commands always end with the number to dial - special tones like * and # can be included in the dial string, a ! does a hook-flash, and commas are used in the dial string for pauses.
• X0, X1, X2, X3, X4 are commands used to vary how and whether the modem will look for a dial tone prior to dialing.
• Commands that start with #V are voice mode commands. Refer to your modem's documentation for the details on these.

For example, the hook-flash transfer string "AT&F0E0X3DT!,,18005551212" is interpreted as follows:

• AT: Attention modem, commands are on the way!
• &F0: Resets modem to original configuration.
• E0: Instruct modem not to echo commands back.
• X3: Instruct modem to not check for a dial tone before dialing.
• DT: Dial with touch tones.
• !,,18005551212: Dial command is to hook flash, followed by two pauses, then dial 18005551212.

Troubleshooting SendModemCommands

It's extremely difficult to diagnose problems with SendModemCommands functions. Every modem seems to exhibit slightly different behavior, and differences in phone systems compound things only further.

Troubleshooting SendModemCommands is something that should be left to experienced computer users. Novices will find this a difficult and frustrating task. To troubleshoot SendModemCommands:

Step 1. Create a Call Tree for testing purposes.

• From the menu bar, choose File .. New Call Tree and create a new Call Tree for testing purposes.
• Click on the Answer_Phone Node.
• When the Edit Node window appears, check the box marked Don't ask a question at this Node.
• Click to the VBScript Macro tab. For the macro, type the following lines:

MsgBox "Start Capture Now."
SendModemCommands = "ATDT5551212"

• Replace the ATDT5551212 on the second line of the macro with whatever modem command string is being tested.
• Close the Edit Node window and test the Call Tree by starting the simulator. To start the simulator, choose Phone Calls ... Simulate Calls from the menu bar.
• Simulate the call, you should get a message box that reads "Start Capture Now". Click OK and the next message box should read "At this point Active Call Center would send the following commands to the modem...". Click OK again and close the simulator.

Step 2. Download and install the PortMon diagnostic utility.

• Go to http://www.sysinternals.com and proceed to the Utilities for your particular operating system. Find and download a utility called PortMon.
• Extract the PortMon files in a separate directory.
• Start PortMon.
• Check that event capture is off in PortMon (look under the Options or other menus for the Capture Events choice).

Step 3. Start the Active Call Center Call Monitor

• Make sure Active Call Center is open and the Call Tree just created for testing is active.
• Start the call monitor in Active Call Center by selecting Phone Calls ... Monitor Phone Lines.

Step 4. Dial into the system and perform diagnostics.

• Dial into the system to start the Call Tree.
• A message box will appear with the message "Start Capture Now" (from the macro in the Answer_Phone Node).
• Leaving the message box showing, start capturing events in PortMon (clear the log if it's not already empty).
• Click OK on the message box, the PortMon window should show lots of activity.
• When the call is disconnected, shut off event capture in PortMon again.
• Close the Active Call Center Call Monitor.

Step 5. Analyze the PortMon log.

• Go to the top of the PortMon log and locate the command string that was sent with SendModemCommands. It should be within the first 5-10 lines on a "Write_Comm" line.
• If the command sent with SendModemCommands cannot be located, it means that the commands are not even being sent to the modem. Look for the command later on in the log, if it still can't be found, there may be an issue with the modem's TAPI driver that prevents sending commands directly to the modem. This is an unlikely and unfortunate end to the troubleshooting process.
• Once the commands have been located, you can be confident that commands are being sent to the modem. The rest of the troubleshooting process will focus on generating the correct commands to achieve the desired results.
• After locating the commands, look for the modem's response. The modem's response is usually on a "Read_Comm" line and will be something like "..OK..", "..ERROR..", "..NO DIAL TONE..", or some other message.
• If the modem's response is "OK", then the commands are being processed correctly by the modem. If the modem is not behaving as desired, then the error must be in an incorrect SendModemCommands string. You will have to figure out how to fix that yourself.
• Proceed to Step 6 if the modem's response is something besides "OK".

Step 6. Change the modem commands to try to eliminate the error.

• If the modem responds with error, try changing the modem commands by adding and removing arguments. For common tasks such as paging and call transfer, try the multiple variations provided earlier in this section.
• If the modem is responding with "NO DIAL TONE" messages, try the Xn commands: X0, X1, X2, X3, or X4. Xn commands shut off dial tone detection and help resolve this error.
• If this your 10th or 12th pass through and nothing seems to be working, start with the basics: "ATH" should always work, it's a hangup string. If that works, then try to find another small command that works, and build your way to a larger command.
• Change the modem command in the macro of the Answer_Phone Node, then repeat the process starting with Step 3. This is a process of trial and error, so be prepared to repeat this many times.

Step 7. If All Else Fails...

• Read the modem manual and/or call the modem manufacturer to find a set of modem commands that work.

Step 8. Once the command works in the test tree, use the command in other Call Trees where it's needed.

Remember: once it can be verified that the commands are actually reaching the modem, the answer lies in finding the correct command string to accomplish the required task.

Conclusion? We have customers that use SendModemCommands successfully for call transfers and numeric paging. It wasn't necessarily easy for them to figure out the specific commands required, but once they did their systems worked without further modification.