Customize DSS key via Configuration File

[CWR]

Allen - you do not mention what firmware you are using or what version of 3cx. Normally I use this in the 3cx Template File. Then when you make an edit to the extension, it recreates the cfg file for the handset assigned to that extension (based on Mac address).
memorykey.1.line = 1
memorykey.1.value = SP1
memorykey.1.type = 10
memorykey.1.xml_phonebook =

But because it is for a T22 without the extra 10 buttons (T38, T28, T26) then you need to use a line key which should be like this:
linekey.1.line = 0
linekey.1.value = SP1
#linekey.1.pickup_value =
linekey.1.type = 10
linekey.1.xml_phonebook =
linekey.1.label = SP1

scramatte - T20 and T26 will each be different if you intend to use the buttons on the side of the T26.

Firmware for the above code should be this or higher:
The T26 should be using: 6.70.0.168 for 3CX
The T22 should be using: 7.70.0.168