title: SMS encryption over GSM
body: <p>I have read this somewhere:</p>
  
  <p>Most mobile operators encrypt all mobile communication data, including SMS messages In GSM, messages are encrypted using A5/1 but even when encrypted, the data held by SMS is readable for the operator. Mobile phone operators have the ability to filter and modify short messages during delivery. Also, it is possible that the operator might not filter messages on purpose but might use equipment that cannot handle encrypted messages.</p>
  
  <p>I want to know..is it true..?
  Can someone explain how this filtering is done..? and is there any solution to avoid such loss of messages on the network..?</p>