IS telephony manager values changeable?
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I want to know if I can rely on the telephony values like country , MCC etc on Android for my app. can I change them on the run using setprop ? I tried changing using setprop it didn't seem to work ? From my understanding telephony manager is a class/interface which represents HArdware configuration of GSM or CDMA. In case of GMS this cud be sim and in case of CDMA it cud be a hard ware. My questions are ,
  Who update these values in both the cases for the first time ? 
  Are these values are saved by OS as read only ?
  What if an user travels to different country or zone will some of the vlues like country code and MCC values updated automatically ? 
  can I reset these values ? 
I have no intention of changing any of these values but want to understand its working!! I would appreciate if some one can help me on this ?

 