     7   6   5   4   3   2   1   0   7   6   5   4   3   2   1   0   7   6   5   4   3   2   1   0   7   6   5   4   3   2   1   0
   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
00 | DTMF system index             | PTT ID type                   | PTT ID mode                   | Connect ID index              |
   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
04 | Disconnect ID index           |
   +---+---+---+---+---+---+---+---+
Where:
  - DTFM system index: 0-based [0,3]
  - PTT ID type: 0=None, 1=Pre-only (default), 2=Post-only, 3=Both
  - PTT ID mode: 0=Never, 1=Always, 2=Once
  - (Dis-)Connect ID: 0-based [0,15]
