You can wire T/R ahead or behind the line card...
This is a new one on me. I have always understood the operation of the 400 line card to be open the A/A1 before T/R and the line gets put on hold. Open the T/R before the A/A1 and the line goes on hook.
The logic involves the sequence of two relays on the card, the line sensing relay in series with the CO line and the A-lead relay. If you connect before the card (the CO line directly) the relay in series with the line will not operate when the T/R opens and closes on the hookswitch. I can't see that doing anything other than a false hold.
-Hal
