(Android function) Call forwarding

I would like to create a function that will forward incoming call, like a switchboard.
I would like to choose which call must be forwarded.
**21* forwards ALL INCOMING CALLS (not usable)

This function must be used into a B4A (Basic4Android) project.
Probably this function can be written in Java too.


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Sub PE_PhoneStateChanged (State As String, IncomingNumber As String, Intent As Intent)
If State = "RINGING" Then
If IncomingNumber = "++441234567800" Then
------>FORWARD

End If
End If
End Sub
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Low budget available. No upfront.
Source-code required for test (no payments before test).