[TriLUG] VOIP soft phone help.

[Thomas Gardner]

Hi folks,

Well, I'm finally getting started on my project.  I won't go into
too much detail, because when I do that sort of thing, I usually hear
snoring (and sometimes it's mine).  The long and short of it is that
I'd like to set up what amounts to a bunch of cheap USB speakerphones
(similar to http://tinyurl.com/8vl35hk or http://tinyurl.com/8qmzzuf),
on a bunch of raspberries (or suchlike) which will all be networked
together, and then conference all these phones together into one big
conference call.  While I'm waiting for equipment to come in for my
prototype systems, I'd like to at least start thinking about problems
that I know are coming.  One of those problems is choosing the softphone
that will be running the USB speakerphones.  I was hoping some folks
out there might be able to help me narrow my search.  Here are some
random thoughts I've been having on the subject:

1) Ideally, I'd like to be able to just conference the softphones
to each other without having to learn more than I have to (like
Asterisk in addition to the softphone software running each USB
speakerphone).  I suspect they all do this, but honestly, I have
no idea.  This is all new to me.

2) I'm concerned about feedback and echo problems.  Although all the
phones I've ordered for prototyping claim to have echo cancellation,
that's really designed to keep the speaker from bleeding into the
microphone on the same unit.  A number of these phones will definitely
be within earshot of each other, and depending on where the person
speaking is, a number of these phones will be able to pick up the
same person talking, each one time shifted slightly due to that pesky
non-zero speed of sound.  I doubt the speakerphones themselves will
be able to figure that out and prevent echo and/or feedback problems
caused by this.  I'm thinking the software is going to have to deal
with that.

3) As icing on the cake, I'd love to have some kind of automagic
volume control for the speaker linked to the ambient noise of
the room, so it would turn the speaker up when there's a lot
of noise, and turn it down when there isn't.  Most (if not all)
of the prototype speakerphones I've ordered are supposed to have
noise reduction circuitry built in, so the computer would never be
able to determine the noise level in the room from the microphone
in the speakerphone, so I'm thinking I'd probably have to add a
microphone just for that, but it would be worth it for at least
one of the locations I have in mind.

4) As a dream come true (really not expecting to be able to do this,
but it's worth asking about), I'd love to be able to set up a ``not
this'' input into the system.  For example, I'd love to have an input
coming directly from, say, a TV or radio into the system to tell
the system to filter out any such stuff coming in from any nearby
speakerphones, so they don't broadcast whatever drivel is coming out
of the idiot box to the rest of the conference call.  Man, that would
be sweet.

So, does anyone have any suggestions for good softphone software that
you think might be able to deal with some or all of the above?

Thanks,
tg.