[Asterisk-Users] how can i connect a cost display on asterisk

[Peter Corlett]

<ht at phonitel.com> wrote:
> Johannes,
> I would be curious to know if there is a solution for this. Another
> solution is that you buy a "call meter". Which is a small box that
> can be placed in front of phone phone and that can display costs.

> FXS--> call meter --> analog phone

> This call meter needs to be programmed with a table inside and a
> rate for each destination.

It depends on the type of cost meter. One of BT's products is the
Meter Pulsing Facility which sends a short 50Hz longitudinal tone on
supervision, and just before a "unit" has been consumed. BT scrapped
unit charging in the mid-90s but this particular bit of legacy
remains. It's intended for payphones where you charge, say, 10p for a
unit and want to know when the 10p has been consumed.

That's why you can sometimes hear a buzz on a BT payphone a few
seconds before the credit drops, because the longitudunal pulse
sometimes breaks through into the audio path, even though shouldn't. I
suspect this is because they payphone isn't properly earthed.

A cost meter (or paypgone) that determines cost without exchange
assistance will suffer from inaccurate pricing information and an
inability to determine the start of supervision. Still, given that BT
charge a hefty wedge for the MPF, some people just stick a COCOT on a
standard exchange line and hope it's good enough that they don't get
ripped off.

-- 
Common sense is the collection of prejudices acquired by age 18.
							- Albert Einstein