[Asterisk-Users] Re: How to generate "ringing tone" to a calling party.

[Rich Adamson]

> > Actually, this is required to work for telco's (I would think this is
> > the same in most countries). Consider premium rate phone services (in
> > Australia, 1-900 xxx xxx) where you are charged $x per 'time unit'. eg,
> > $5/minute etc... The service operator is required to tell you how much
> > the call will cost, and allow you to dis-connect and avoid all charges.
> > Of course, the way this is done is to play the message before answering
> > the call. Once you answer the call, the telco begins charging, and you
> > begin providing the 'service'.
> >
> > As I said, I would be interested in being able to deploy this properly,
> > as it means that people calling from long distance/mobiles don't have to
> > pay while they are waiting for a real person to answer. I imagine this
> > would also have a rather positive effect for people who have inbound
> > 1300/1800 numbers (where you are charged for the incoming call, I assume
> > from the time you answer the call).
<snip>
> 
> This allows the called switch to not only generate audible ringing but
> also an intercept recording, "The number you are calling has been changed,
> the new number is...", "All circuits are busy now...", etc.
> 
> I don't think the 900 pay-per-call services use this model, but instead
> have a built-in "grace period" in the billing mechanism after answer.

Come on guys, each of the examples that have been reflected in various 
postings have some real world truth, but you can't make a generic 
statement that all called telephone numbers provide one-way audio. 
Those were "toll avoidance" and "paystation" issues addressed way over 
20 years ago (at least in the US).

Examples:
1. two-wire analog pstn lines: as soon as current draw is sensed by
the central office, answer supervision is generated by that "central
office", period. It has nothing to do with whether * handled it or
whether an analog phone is hanging on the end at the customer's
location. There is no such thing as one-way audio or grace periods.
2. Trunk lines from the Central Office to a customers site: can be
configured at the central office in many different ways and is
dependent on the "service" requested/provided. One-way audio, grace
periods, etc, are oftentimes dependent upon exactly which Central
Office switch the telco is using (eg, Nortel, Siemens), and whether
the telco "chooses" to support those options.

A PRI is considered a trunk line; a BRI is not. An ordinary analog
pstn fxo interface is not a trunk.