[c-nsp] ARD signalling (for trading turret systems)

[Dave Temkin]

Has anyone else attempted to port TDM ARD's over an IP network?  I'm
currently working on a project to do so, and I'm finding that Cisco
doesn't support PLAR signalling (not to be confused with the PLAR
connection mode).

PLAR signalling is akin to FXS/FXO/E&M (the signalling bits are actually
the exact inverse of E&M).   Right now for the ones I've set up I've had
to do this kludge on every voice port:

voice-port 4/0:1
 condition tx-a-bit invert
 condition tx-b-bit invert
 condition tx-c-bit invert
 condition tx-d-bit invert
 condition rx-a-bit invert
 condition rx-b-bit invert
 condition rx-c-bit invert
 condition rx-d-bit invert
 connection plar 54107

controller T1 4/0
 ds0-group 1 timeslots 2 type e&m-immediate-start



The other issue here is DSP resources.  PLAR signalling has a nasty habit
- the bits for PLAR look like this:

0000 = Ringing or off-hook
1111 = On hook

So, when a T1 goes down, every single channel on that T1 starts ringing.
Not pretty.  It also will consume every DSP resource in an oversubscribed
router causing blocking.

I know we could go back to FXS/FXO for each of these but it's always a
hassle because the carriers get the two confused when delivering circuits
and it's a pain to get it corrected.

Just curious to know what others in the industry are doing.

Thanks,
-Dave