If the conversation you are interested in is only done PERSON TO PERSON in a room in Trump Tower, all the winks and nudges to AT&T won’t help at all.
It requires a listening/recording/transmission device in or on the outside of the room.
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It can be accomplished with a malicious program inserted into the buildings VoIP servers/switches to turn every phone into a listening device. possibly a simple reprogram , possibly through a replacement of a prom/eeprom chip.
AT&T is the root of all evil, seriously I dislike them intensely. The overt spying devices they are responsible for installing are all over the interstates. It is just unreal!
Since 2009 the CPU die includes a separate stand alone processor independent of those available within the system. Only the chip manufacturer has access to it’s program, or whomever leans on them.