The CTI Client Professional includes an integrated SIP SoftPhone.

So you only need a headset to use your PC as a simple SIP Softphone in conjunction with a VoIP provider or a local VoIP system.


The integrated SIP softphone supports the following functions:

  • Dial, hang up, accept call, hold, consultation, transfer, pickup
  • DTMF dialing
  • Audio-Codecs: G.711 (A-Law and U-Law)
  • DND
  • Busy Lamp by SIP-SUBSCRIBE

Conditionally supported functions:

Unsupported features:

  • voice encryption


Under [Options > Phone Dialog (TAPI Device) > Select > VoIP] select the "SIP SoftPhone".

  • The entry is only visible / available in the Professional version!
  • A new SIP registration is to configure via the button [Device Configuration].
  • Later you reach the configuration via: [Options > PhoneDialog (TAPI Device) > Driver Configuration > Edit].

User ID / authentication name / password

The necessary data for "User ID, Authentication Name and Password" can be obtained from your SIP service provider.

The user ID often uses the phone number, but it can also be a customer ID, for example.
Specifying an authentication name is optional. If no authentication name is entered, the user ID is used for the authentication process.

Audio Settings

You can configure the audio-settings via: [Options > Audio...]

  • Here you determine the sound devices for microphone and Headset loudspeaker as well as their volume.
  • Under "Extended Settings..." you can:
    • set the ring tone volume and let signal phone calls if necessary over a second sound device (e.g., speaker),
    • declare own WAVE files for the ring tones.
  • See also: Troubleshooting - Audio connection does not work

Wireless headsets

The CTI Client supports special wireless headsets, so that a call can be accepted and hung up via a button on the headset (in principle).

  • Terminal Server / Remote Desktop:
    If the CTI Client is installed on a terminal server or operated via remote desktop, the call answer/hanging-up via headset does not work (for technical reasons).

The configuration is made via [Options > Audio > Advanced Settings].

Unfortunately, it can not be guaranteed that call-answer / hang-up using the headset button will work with all models of the listed manufacturers.
And even with the tested models, there were problems on individual Windows PCs.

The headsets of the following manufacturers are supported:

  • Jabra / GN Netcom
    • Tested models: "Jabra PRO 930", "Jabra EVOLVE 65 UC" and "Jabra Stealth UC MS".
  • Plantronics
    • Tested models: "Savi Office", "CS60"
Hints to Jabra Headsets
  • As of version 3.0.051, the CTI Client no longer requires "Jabra Direct" software.
    • If the "Jabra Direct" software loses the connection to the headset several times at the start of the CTI Client, you should uninstall the "Jabra Direct" if possible.
  • In the CTI Client, under [Options > Audio > Profile - Edit > Special Headset Functions] select "Jabra".
    A click on the "Test" button should display "OK".
  • Now you can try to answer a call using the headset key.

Up to version 3.0.050:

  • The Microsoft .NET Framework 3.5 must be installed on the PC.
  • The "Jabra Direct 1.0" software must be installed on the PC.
  • If the headset is connected to the PC, the Jabra Direct software should show "Device ready for use".
  • In the Jabra Direct software, click "Device Settings" and set "Preferred softphone" to "Standard softphone".(see screenshot)
    • The setting as "standard softphone" is important for the call signaling on the base+headset to work as well as the call acceptance on the headset.
  • In the CTI Client, select "Jabra" under [Options > Audio > Advanced settings > Special wireless headset].
    A click on the "Test" button should display "OK".
  • Now you can try to answer a call using the headset key.
Hints to Plantronics Headsets
  • The "Plantronics Hub" software must be installed on the PC. On the download page, supported models are listed.
  • If the headset is connected to the PC, this should be displayed in the Plantronics Hub software on the "Info" tab.
  • In the Plantronics Hub software, click [Settings > Softphones]. You can set the "Target Softphone" to "None".
  • In the Plantronisc Hub software, click on [Settings > Ringtones & Volume] and switch off the PC ringtone here.
  • In the CTI Client, under [Options > Audio > Profile - Edit > Special Headset Functions] select "Plantronics".
    A click on the "Test" button should display "OK".
  • Now you can try to answer a call using the headset key.
  • Note to Savi Office:
    • In the case of an incoming call, the LED "PC/VOIP" should be switched on at the base station. It may be necessary to specify "PC" as the default in the Plantronics Control settings.
    • The call signaling and call answer only work if the headset is in idle mode. If the headset is taken from the base (without a call), it will be automatically activated. Then press the button twice on the headset, so that it goes again Idle.
Notes on HID Compliant Headsets

Some headsets (e.g. from Sennheiser) have a button for call control and report in the Windows device manager in the group "Input devices (Human Interface Device)" as "HID-compliant headset". That is, the headset button is reported as a normal keyboard event. The CTI Client can recognize this keyboard event and use it to accept calls and to hang up.

Troubleshooting (Jabra/Plantronics)

If call answer by the headset key does not work:

  • Restart the computer.
  • If the headset has a docking station: Disconnect them temporarily from the power supply to force a reboot.
  • If the headset includes a Bluetooth dongle: Use the Bluetooth dongle!
    • If the headset is directly connected to a laptop via Bluetooth (without a dongle), the call answer function via the headset button does not work.
  • Try to connect the headset to a different USB port.
  • Connecting via a USB hub can also cause problems.
  • Two parallel headsets from the same manufacturer may interfere with each other (for example, Jabra Stealth and Jabra Pro 930).
  • If the headset is paired with a smartphone, the PC may not receive the click on the headset. Then the PC has e.g. receive only OnAudioStateChanged events (from a Plantronics headset).
  • The CTI Client does not require "Jabra Direkt" software. At least for one customer, "answer on headset" was working after uninstalling the "Jabra Direkt" software.
  • Try the headset on another computer.

If the activation of the audio connection to the headset blocks for several seconds:

  • Restart the computer/laptop.

SIP SoftPhone in a terminal session

Can the CTI Client be used as a SIP-Softphone in a terminal session?

In principle, yes. Under the RDP settings / Local resources, the audio recording and playback is to be activated. You would have to test whether the audio quality meets your requirements. Should there be unacceptable speech delays or audio dropouts, a switch to physical SIP telephones would be recommended.
Further restrictions:

  • Call answer on the headset is not supported.
  • Call signaling via a second loudspeaker is not supported.

Notes for some functions


[Options > PhoneDialog (TAPI Device) > Driver Configuration > Edit > SIP Service Provider > Settings > Tab "Features"].


If you are in a call and click on a speed dial key, the active call is automatically held and a consultation call is established. Further possibilities for initiating a consultation ...


For the "Pickup" function, the corresponding pickup code of your telephone system must be entered under the Tab "Functions":

  • For a pickup group, you may only need to enter the pickup code. Frequently *8 is used for pickup.
  • For direct pickup, the extension number must also be dialed in (eg *8234). In this case, the hook is to be set at: "+ Phone number".
    The "Direct Pickup" is done via the right-click menu of the speed dial buttons or via the pickup tool button from the PhoneDialog.
Call transfer

From version 3.1.008 two transfer modes are supported. The details of the A and C subscribers relate to the transfer of an incoming call.

  • REFER C to A: The caller is connected to the consultation call.
  • REFER A to C: The consultation call is connected to the caller.
Conference Call

The SIP SoftPhone component can not switch conferences by itself. Under [Options > PhoneDialog (TAPI Device) > Driver Configuration > Edit] you can select an alternative conference mode:

  • personal conference room: If you have a personal conference room in the telephone system, you can enter the conference room number here.
    One conference room is required for each CTI Client user. The conference room must not require a PIN input. It would therefore be advisable to use a longer (secret) conference room number. These conference rooms should also not require name announcements.
  • 3-Party-Conference via DTMF *3: Customers of "Deutsche Telefon Standard AG" can use this mode. The conference function is also to be activated by "Deutsche Telefon Standard AG". 
    Hint: Under the [SIP Service Provider > Settings], the DTMF mode should be set to "RFC 2833".
  • A prerequisite for switching a three-way conference is that you have already set up a consultation call (a held call and an active call).
Call Forward / Do Not Disturb

Call forwarding and call protection can be switched via the icons at the bottom right of the orange PhoneDialog display.

  • Programming directly in the telephone system:

    • The corresponding codes are to be configured on the Tab "Functions".

    • To set call forwarding, the CTI Client dials the corresponding code + phone number.

    • Advantage: Call forwarding / call protection are also active when the CTI Client is closed.

  • Otherwise, the CTI Client will handle call forwarding / call protection.

    • Advantage: The diverted/blocked calls are entered as missed in the journal.

    • Disadvantage: Call forwarding / call protection are only active when the CTI Client is running.

Active call forwarding / call protection applies to all registered SIP accounts. If several SIP accounts are active, but a call forwarding should only be set for one account, then you can assign a speed dial key with the corresponding programming code.

CLIR (phone number suppression)

If necessary, the transmission of your own telephone number for a call can be suppressed by means of a code prefix. The corresponding CLIR code can be entered on the Tab "Functions". Then the CLIR switch is available in the PhoneDialog.

DTMF (Postdialing)

You need the DTMF postdialing, for example, for voice announcements with menu selection.

  • "RFC 2833" (default): The tones are transmitted as digital commands in the audio channel.

  • Inband: The tones are generated directly by the CTI Client and transmitted in the audio channel.

  • SIP-Info: The sounds are generated by your telephone system.

Outside Line Access Code

If you have configured accounts from different SIP providers and only one SIP provider requires an outside line, you can optionally set an outside line code.

Voice recording

The integrated SIP-SoftPhone from version 3.0.060 has a toolbar for controlling the voice recording. Recordings can be started, paused or ended during a call.

Please note that the consent of the conversation partner is required before voice recording.

You can find further information on the functionality and configuration of the voice recording under [Options > Audio].

Voicemail Indicator

If you want to see if there are new voice messages, you would need to configure a special speed dial key:

  • [Right-click on a speed dial key > Edit ...]
  • Set the "Action Type" to "Dial Programming Code".
  • Enter as "Button name" e.g. "VoiceMail".
  • Under "Dialing sequence" enter the key combination to query voice messages.
  • On the right under "Monitor-LED" click on the button "..." for the TAPI device selection.
  • In the TAPI Device selection on the left, select [VoIP > SIP SoftPhone] and on the right a free "SIP Monitor" line and click on the button "Device Configuration" below.
  • Enter your data in the following dialog and select the "Voice message waiting indicator" mode.
    Close the dialog with "OK".
  • Close the TAPI Device selection dialog with "OK".
  • Close the speed-dial config dialog with "OK".
  • Now the speed dial button should show a red LED as soon as there are voice messages.
    • The button tooltip text displays the number of voice messages. The info text is transferred 1: 1 from the telephone system.
    • Tip: If you switch the speed buttons to "Large buttons", you will immediately see the number of voice messages.

Monitoring / Busy Lamp Field

a) Monitoring via CTI Server

The CTI Client can report its call status to the CTI Server and this then distributes the status to all other CTI Client instances.

Recommended configuration via CTI Server + Speed Dial Panel:

  • In CTI Server, all clients are to configure user-related with name, first name and phone number.
    Hint: The Client must not be assigned a TAPI device in the server!
  • Then, in the Server is to create a group with all needed Clients.
    By group rights may be determined for example whether the caller phone numbers should be visible to all.
  • The group is then to integrate in the CTI Client as a speed dial panel via [Options > Speed Dial > Link CTI Server Group Panel].
  • More information to configuring...
b) Monitoring via SIP-SUBSCRIBE

The CTI Client Professional also provides SIP monitor lines based on the SIP-SUBSCRIBE protocol that signals "ringing", "talking" and "idle" states. The caller numbers are usually not transmitted/displayed.


  • In the CTI Client, right-click a blank speed dial key and select "Link Monitor LED".
  • In the next dialog, select "SIP-SoftPhone" on the left and a "SIP-Monitor for xxx" line on the right.
  • Then click on "Device configuration ..." below and configure the SIP monitor line with the number to be monitored. For the authentication you have to use your own SIP account.
  • Hint: In the basic configuration, only 3 SIP monitor lines are displayed. But once you have configured a line, an additional free line is automatically provided.


Audio connection is not working
  • Windows 10: [Start > Settings > Privacy > App Permissions > Microphone > "Allow apps to access your microphone"] must be set to "On".

  • If you use an extra antivirus software, please switch it off as a test or add an exception for "cti_client.exe". On Windows 10, for example, Kaspersky could block the microphone. Call acceptance, hanging up or the status display may not work either.

  • If you are using an external VoIP provider (cloud) and the internal parties (CTI Client to CTI Client) do not hear the each other:

    • For each CTI Client, configure a different local port under [Options > PhoneDialog (TAPI Device) > Driver Configuration > Advanced > First Port used locally]. Each CTI Client should have its own port area (10 ports).
      Example: CTI Client 1: local port = 6000; CTI Client 2: 6010; CTI Client 3: 6020

    • Hint: For the SIP control, the CTI Client uses the specified port. For audio then the next available ports are used.

  • VPN: If the telephone system is connected via a VPN connection, the IP address of the VPN connection may have to be configured as "external IP" in the system. Example Yeastar PBX: [General > SIP > NAT > NAT Type = External IP Address].

You do not hear the other party
  • As a test, deactivate under [Options > PhoneDialog (TAPI device) > Driver configuration > Edit > SIP service provider - Settings] the checkmarks for "Evaluate parameter 'received'" and "STUN server". Then restart the application once.

The other party only hears you after 5 seconds

This has occurred in connection with "Poly EncorePro 310/320" headsets.

  • An update of the headset firmware may help to solve the problem.

Audio connection is rushing heavily

Very strong noise can result from incompatible speech coding. To troubleshoot, you could test the following setting:

  • Set [Options > PhoneDialog (TAPI Device) > Driver Configuration > Advanced > Preferred Audio Codec] to "A-Law" and check "Support only this codec".
Ghost calls / fake calls

If calls appear in the CTI Client that do not come from your VoIP provider / telephone system, then the following option could solve the problem with the fake calls: [Options > PhoneDialog (TAPI device) > Driver configuration > SIP registrations - Edit > SIP service provider - Settings > Use connected UDP socket].

More information

  • During a conversation the volume can be adjusted for microphone and speaker in the "PhoneDialog".
  • You can accept an incoming call by hotkey "Break Key". To activate the hotkey see [Options > Telephony].