XPost: comp.mobile.android   
   From: grschmidt@acm.org   
      
   On 01/06/2020 05:39, Arlen Holder wrote:   
   > Tough question... likely only for Android freeware experts...   
   >   
   > How does incoming "Calling Number Identification" work and more specifically   
   > is there a method you know of to CONTROL its source data?   
   >   
   > Essentially, the goal is to shift incoming CallerID off of the   
   > system internal default contacts sqlite database onto a   
   > given privacy-oriented contacts database of your own choosing.   
   >   
   This is part of the relevant telephony standards, this is a basic how it   
   does it on GSM, ignoring ACKs and errors and stuff.   
      
   Tower sends a RING packet.   
   Tower sends a (possibly empty) "Calling Number Identification" packet.   
   Tower sends RING packets until:   
       - answered - tower sends and receives voice packets   
       - re-directed - tower sends and receives voice packets   
       - cancelled - call is disconnected   
       - times out - call is disconnected   
   Etcetera.   
      
   That's it.  To get a look at the "Calling Number Identification" packet   
   you have to look inside the "call" application.   
      
   The actual layout of a "Calling Number Identification" packet is beyond   
   the scope of this newsfroup, a deep-dive into the source of the Android   
   "call" application would be required.   
      
   	Cheers,   
   		Gary	B-)   
      
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