[VoIP] 2600 Flashing Supervision

[Donald Froula]

I added a flashing 2600 test number to my box at:

1-762-2600/2601
<2600> KP+199+ST

This number plays back 2600 at .5 second on/.5 second
off for 8 seconds, then .25 on/.25 off for another 60
seconds, kind of like the old supervision tests.

When dialing direct on Asterisk from a local extension
(not through the SF trunk group), it sounds like 2600
Hz. busy and reorder.

However, when dialing through the SF trunks, one can
clearly hear the action of the SF notch filter.

What one hears is a cheep of 2600 when the tone is
applied, another cheep when the tone is removed, and
the old warbling noise in-between. The warbling is due
to the rather high level of 2600 and imperfect tone
filtering of the notch filter.

This confirms that the cheeps we sometimes hear while
a call completes and supervision is returned through
ProjectMF are not real winks, but artifacts of the
tone filter operation.

Note that the reverse 2600 will not blow off the call,
as I have the near-end trunk group "goodied" through
the Zaptel settings. However, the notch filters still
work fine, making this observation possible.

Best,

Don