how to detect "no carrier" SIM card mode ?

[peacemaker]

I mean the low GSM signal and the cellular network is lost now.
How about dual sim device ?

 

[peacemaker]

Found myself

Sub phl_onServiceStateChanged(State As Int, strState As String)
Log("ServiceStateChanged = " & State & "; " & strState)
ServiceState = strState
If State = 1 Then 'State = 1; strState = "OUT OF SERVICE"
tim.Enabled = True
Else If State = 0 Then 'strState = "IN SERVICE"

http://www.b4x.com/forum/additional-libraries-classes-official-updates/12377-phonestatelistener.html