Telephone training system with Asterisk?

We are running a school for foreign languages training students for office communication. This includes telephoning in foreign languages. Up to now, we provide a simple one-box unit with a wireless for the person that leaves the classroom and a loudspeaker for the class to listen.

There was the idea of building a telephone system that allows to simulate telephone calls to far destinations and to mobile phones offering kind of simulating distortions typical to such calls (delays, cracks, echos, or scenarios like “mobile phone at a busy street café” :smiley: ).

With Asterisk, my phantasy goes to offer the trainer an easy interface to choose line quality, scenarios etc. and to have a telephone in every room (and maybe a few wireless ones) to call from and to be called. One might even simulate international numbers…

Has anyone here ever seen something like this with Asterisk, or are there any plugins/modules you would consider worth taking a look at? I am new to Asterisk, so I don’t know what to look for.

Let me add this: There is a Linux server running 24/7 and a terminal for the teachers in every classroom.

Thanks for all hints!

Rolf

Hello.

As for me, I never faced any Asterisk modules which imitate bad line quality or some strange noise (cafe/railway station/etc).

I think it’s better to record any voice phrases you like and add some noise to them in a sound editor. And only then to put phrases to your dialplan.

There are also 2 functions in Asterisk which you may consider being helpful:
VOLUME - wiki.asterisk.org/wiki/display/ … ion_VOLUME
PITCH_SHIFT - wiki.asterisk.org/wiki/display/ … ITCH_SHIFT

I think you can simulate bad line quality with any traffic shaper or policying/prioritization (‘tc’ utility from ‘iproute2’ package in GNU/Linux, ‘altq’ in OpenBSD Packet Filter, Cisco IOS tools, etc).

lartc.org/lartc.html
openbsd.org/faq/pf/queueing.html

Thanks for your ideas, here are some spontaneous thoughts:

[quote=“Lexus45”]Hello.

As for me, I never faced any Asterisk modules which imitate bad line quality or some strange noise (cafe/railway station/etc).

I think it’s better to record any voice phrases you like and add some noise to them in a sound editor. And only then to put phrases to your dialplan.
[/quote]

Yes, any noise would have to be added, that’s sure. But line quality could be influenced.

That’s a good idea, if you can quickly change these parameters (I mean, quickly enough to let it sound like a short line error).

[quote]
I think you can simulate bad line quality with any traffic shaper or policying/prioritization (‘tc’ utility from ‘iproute2’ package in GNU/Linux, ‘altq’ in OpenBSD Packet Filter, Cisco IOS tools, etc).

lartc.org/lartc.html
openbsd.org/faq/pf/queueing.html[/quote]

Also a good idea, but it would have to influence the traffic on the telephone line only, not the internet and other traffic. Might cause some fiddling, but I could imagine that one might slow down network traffic far enough to make it sound uggly… :smile:

What I had in mind was kinda API to the core transport and/or modulating functions. Something to slow down modulation for a second, then let it come up again. Or add some other noise to the data stream. A nice little peace of software by myself would help modulating these things and offer a handy display to the user.

But I am aware that 99 % of the Asterisk users don’t want to decrease their lines :smiley: so it will be some means of improvisation, like you proposed.

Thanks a lot for the links!

Rolf