Function keys
The device has touch function keys which you can program to suit your needs. Each function key has a multi-colour display that indicates its status, based on its assignment.
The number of programmable function keys on the device can be extended by adding up to three COMfortel D-XT20 or D-XT20i key extension modules (not included in the scope of delivery). Modules are attached to the right-hand side of the phone.
*Note: If you connect more than one key extension module, use a COMfortel D-XT-PS power supply unit (not in the scope of delivery).
The programmable function keys on the key extension module can each be defined three times (on three levels).
*Note: New parameters have been defined for some function keys (e.g. Speed dial) from firmware version 1.10. If functionality is restricted following an update to a higher firmware version, it might be sensible to delete the particular key and then configure it again.
LED signalling 
Each LED indicates the status depending on the key definition.
*: The function key or the described behaviour of the LED is only visible if the function key has been provisioned by a PBX or activated by manufacturer templates.
**: The function key or the described behaviour of the LED is only visible if the function key was added by importing the corresponding template.
Function
LED display
Status
Speed dial
shining red
Outgoing call from speed dial number or currently active conversation on speed dial number
flashing red
Inbound call to the speed dial number
flashing green
Missed call from speed dial number
shining green
Registered target subscriber
off
No active calls or conversations
flashing yellow
Sending subscription to PBX
shining yellow
Subscription failed
unregistered target subscriber with enabled functionSignal presence
Identity
shining green
Active, registered identity, not a standard identity
off
Active, registered identity, not a default identity
flashing yellow
current registration attempt
shining yellow
incorrect identity
Call waiting
shining green
Function enabled
off
Function disabled
Do not disturb
shining red
Function enabled
off
Function disabled
Flashing red *
Time gap between pressing the function key and acknowledgement by the PBX/provider
Flashing yellow *
Current attempt to register the function key on the PBX/provider, using SIP Subscription
Shining yellow *
Error
Automatic configuration switching*
shining green
Function enabled
off
Function disabled
Bluetooth
off
Bluetooth not active
shining green
Bluetooth active
shining yellow
Error: perhaps no Bluetooth dongle inserted
Browser
None
DTMF-Relay
None
DTMF call
None
Group, Group (incoming), Group (outgoing)*
shining green
Logged into the group
off
Logged out of the group
flashing green
Login process
flashing yellow
Sending subscription to PBX
shining yellow
Subscription failed
Activate config*
shining green
Active configuration
off
Configuration inactive
Mute ringing
shining red
Ringer is off
off
Ringer is on
Park position
shining red
Call in the internal park zone
off
Free park position
Pickup list
None
Pickups
None
Cleaning
None
Relays
Flashing green (approx. 2 sec.)
Relay has been switched
Anonymous call
shining green
Function enabled
off
Function disabled
Call forwarding, on busy, on no reply, Immediately
shining green
Function enabled
off
Function disabled
Flashing green *
Time gap between pressing the function key and acknowledgement by the PBX/provider
Flashing yellow *
Current attempt to register the function key on the PBX/provider, using SIP Subscription
shining yellow
Error, function key perhaps not completely configured
SIP message
None
Default identity**
shining green
active and registered identity
Silent Alert
None
Call forwarding ext. Calling, on busy, on no reply, Immediately*
shining green
Function enabled
off
Function disabled
flashing green
Time gap between pressing the function key and acknowledgement by the PBX/provider
flashing yellow
Current attempt to register the function key on the PBX/provider, using SIP Subscription
shining yellow
Error, function key perhaps not completely configured
VPN
shining green
Function enabled
flashing yellow
Establishing VPN connection
off
Function disabled
XML Minibrowser
None
Configuration
Web interface: 
Function keys
*Details about the settings are in Function keys
Phone: 
Settings > Function keys
or
In the touch function keys area on the home screen > Add entry to list
*Details about the settings are in Function keys
Provisioning: 
*Further help in the Auerswald DokuWiki
Process for assigning function keys using the phone 
Setting up a new function key on the telephone:
Add entry to list
Assigning a function to a free position between 2 function keys on the telephone:
Use the directional pad keys to navigate to the relevant position.
Insert
The new key is inserted above the selected key.
The numbering of subsequent keys is adjusted.
Setting up a new function key on the COMfortel D-XT20/-XT20i key extension module:
Press a key that is not assigned (keys that have a function assigned to them shine yellow).
*Note: If a key to which a function has not been assigned is pressed for a longer time (long press), the menu for configuring the selected key opens automatically.
If necessary, change between key levels by pressing the control rocker.
Process for assigning function keys using the Web Interface 
1.Select a button to which a function has not already been assigned.
2.Change to the right level, if required (Level 1– 3 tab, only extension module).
3.Select the function that is to be assigned to the key.
4.Set other necessary parameters, if necessary.
5.Save your settings.
The assigned key label is displayed on the display.
The key can be used with the function that has been assigned to it.
Extending the range of functionality using provisioning 
You can use the templates in a provisioning file to extend the range of functions on the phone. These additional functions can be assigned to function keys.
Requirement for use
Provisioning from PBX search enabled
*Further help under Using provisioning
PBX firmware from Version 7.4
Suitable template < > phone assignment on the PBX
During the next provisioning process, the configurations in the template file are loaded into the phone. The additional PBX functions are in the Choose a function (phone) or Function menu (web interface) and can be assigned to the function keys.
*Further help in the Auerswald DokuWiki
Configured speed dial number can have a picture assigned to it 
You can assign a picture, e.g. of the contact person involved, to a configured speed dial number, making it easier to assign a subscriber number to a contact.
Requirement for configuration:
The URL of the external server on which the picture is stored
or
picture with Base64 encoding
Speed dial number is configured
*Further help under Speed dial
*Further help in the Auerswald DokuWiki
Function key icons can have a picture assigned to them 
You can assign a different image to a function key, via provisioning or in the web interface, enabling you to create a personalised user interface.
Requirement for configuration:
Image file in one of these formats
.jpg
.png
.bmp
.gif (animations are not displayed)
*Link to video (only in German) https://www.youtube.com/watch?v=bYMfJZkbuyU
*Details about provisioning this function in the Auerswald DokuWiki