Even though this question is not a pure programming, but i think it is useful to share the solution here.
the Avaya One-x Agent application stores the agent ID in the settings file under the following path
C:\Users\admin\AppData\Roaming\Avaya\one-X Agent\2.5\Profiles\default
line # 15
<Agent Login="6666" Password="" AutoLogin="false" Disabled="false" SavePassword="false" ReadOnly="false"
so, you can use the following code to store the Agent ID in a variable and use it for popup purposes.
Const ForReading = 1
Dim AgentID
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objTextFile = objFSO.OpenTextFile("C:\Users\admin\AppData\Roaming\Avaya\one-X Agent\2.5\Profiles\default\Settings.xml", ForReading)
For i = 1 to 14
objTextFile.ReadLine
Next
strLine = objTextFile.ReadLine
AgentID = mid(strLine, 19, 4)
msgbox (AgentID)
Regards