The "ringing" sound, so many rings etc is a complete red herring.
What the caller hears and what the phone does are two very separate things. When a call is sent to voicemail, the signaling message from the voicemail system that acknowledges the call causes the ring tone to be played. Once the VM system has allocated the resources to answer the call, it sends the answer message, and the call sequence continues. Most of the time, the call is acknowledged and answered simultaneously, hence no "ring" before the VM system answers. Sometimes, it doesn't. So you hear a short ring before it answers.
The handset itself does not generate a ringing tone that is heard by the caller. Network equipment does this, usually the main switch (MSC).
As has been said, this is a vein of information that the authorities will have been looking into. Whether they wish to share their findings is another matter.