Conference Call Technical Bulletin
The person making the conference call on the
phone system can hear the outside parties
OK, but the two outside parties
have a hard time hearing each other.
I hear this all the time!
Actually I've been
hearing it for over 30 years. Even some old electro-mechanical
phone systems would do conference calls - as badly as today's modern
systems do on POTS lines.
This Bulletin also applies to phone
systems that have a feature that transfers a caller outside of the
business, using two lines, often called External Call Transfer. All those systems do is conference the two
lines together, without having a caller in the middle staying on the
line while they talk. Without an inside caller on the conference, the
off-premise transfer is usually a little better than a
THE QUICK FIX for "CAN'T HEAR" ON
If you don't want to know why it's not working, here's
the quick and easy solution to low volume on conference calls that I've
been using for over 25 years on every new phone system
Order 3-Way Calling from the phone company on all the analog CO lines
2. Program a Flash Key on
every phone if it's not built-into the phones
3. Train the users to hit the
Flash button when they're talking to someone (on an incoming or outgoing
call), hear the boop boop boop boop, dial the number they want to
conference in, and hot the Flash button again to conference everybody
Since the conference is being done in
the CO on the 4 wire side, the volume of the conference will be
perfect for all parties - inside and out.
If you are selling one of the phone systems with an
amplified conference, you don't need to do this (well, maybe).
Technically speaking if you have T1s / PRIs or SIP trunks
you shouldn't need this because they are "four wire" trunks with
separate transmit and receive (see further explanation below) - so there
won't be feedback if the gain is boosted.
BUT, some systems just have a crummy
conference even using four wire trunks. 3-Way Calling (using the flash
button to make a conference call on the same trunk) may not work on the
T1 / PRI lines or SIP trunks, so there may be no fix for the problem.
You'll have to try it on any particular installation.
THE QUICK FIX FOR EXTERNAL CALL
Most phone companies
offer the feature Off Premise Transfer on their POTS lines. It works just
like the phone company's 3-Way Calling, except when you hang-up after
making the conference the call is transferred to the other party, rather than
you having to stay on the conference. You need to be able to do a hookflash on
the CO line, just like you do with 3-Way Calling.
This is the same feature that Centrex uses to allow a Centrex user to
transfer the call to another extension, or to an outside party. Some phone
companies may not have bought that feature from their CO vendor, so it's
probably not available on all exchanges in your area (the phone company will say
"It's not tariffed").
This method of External Call Transfer is much better than using the
phone system to transfer the call outside, since the phone system will use
two lines and this only uses one line until the transfer is made, and
then it's using no lines. AND
the volume between the two parties is perfect because the call is
connected on the 4-wire side of the phone company's equipment, just like a
normal phone call.
Most of the companies trying to do an Off Premise Transfer (External
Call Transfer) want to do it automatically from their Automated Attendant.
There's no reason an Automated Attendant can't do it if it can do a flash on a
CO line, except the people who design most Automated Attendants and voice Mail
systems are clueless and don't include that ability. It's not rocket science.
They just don't know anything about phones.
We do sell the Ultimate
Call Handler that you can put on a single line station port on a phone
system. You would program it to answer the call transferred by a human or
Automated Attendant to the station port, do a hookflash, dial the code to do a
CO line hookflash, dial the number you want to transfer the caller to, and
hang-up. If you can do all that with a butt-set on the analog station port, you
can do it with the
Ultimate Call Handler. (try it with your butt-set first!)
You can do the same thing with the
Ultimate Call Handler
if you can't get Off Premise Transfer using the phone company's 3-Way
Calling feature (you need 3-Way Calling on all the POTS lines
you'd ever want to transfer, just like you'd need Off Premise Transfer on
all the POTS lines you'd want to transfer if your phone company offers it). In
that case you would transfer the caller to the analog extension with the
Ultimate Call Handler,
do a hookflash, dial the code to do a CO flash, dial the number you want to
transfer the caller to, do another hookflash, dial the CO line flash code again,
and the incoming caller is connected with the person you wanted to transfer the
caller to through 3-Way calling from the phone company. In this case, the
Ultimate Call Handler
will stay on the line until the call is finished. But only 1 line is ties up,
and the volume between the parties is perfect because it's all being done on the
4-wire side at the CO.
When using these methods you have to take traffic into consideration. How
many Ultimate Call
Handlers and analog station ports (in a hunt group) will you need to
handle as many calls as you need to simultaneously transfer? Or you need to
program the Automated Attendant to take a message or do something else if the
extension with the
Ultimate Call Handler is busy.
THE NOT SO QUICK FIX FOR "CAN'T HEAR" ON CONFERENCE CALLS
For multi-party conferences, Conference Bridges with
special hybrid circuits are available for 2
wire lines which separates transmit from receive, turning them into 4
wire lines for the purpose of adding the correct amount of amplification
in each direction
to make the conference call sound good, and then turning them back into
2 wire lines.
Modern Conference Bridges use DSPs (Digital Signal
Processors) to separate transmit from receive and amplify the lines, which do a pretty good
job (not cheap). Older Conference Bridges use analog circuitry, and work
OK except that there is less separation between transmit and receive.
Since there's less separation, and the transmit side can see the receive
side more, there is some chance that there will be feedback or ringing
during the conference call from time to time.
buy a conference bridge that will work on analog station ports (or POTS lines).
Well, it works sometimes. A conference bridge made for a T1 is likely to work
It's definitely overkill if you only want to add someone into the
call you're on. For arranged multi-party conferences a conference bridge works
The biggest problem using a conference bridge is that the person setting
up the conference needs to have a cheat sheet of how to add parties to the
conference (it's usually not obvious). But they can get used to that pretty
quickly. It would be the same when using one of the zillion dial-in conference
bridges that charge per minute (which is a reasonable solution for more than two
We don't have anything to do with this company, and I've
never used their stuff, but I've never heard anything bad about Forum
Communications conference bridges (I've recommended them to a lot of
companies through the years):
A conference bridge works well on phone systems that send an open-loop
disconnect (CPC signal) out the analog station port when the outside party
hang-up. Unfortunately, most phone systems don't provide an open loop disconnect
on analog station ports. That means that without checking to make sure the
conference bridge is compatible with any particular system you're installing it
on, when one of several parties on the conference hangs-up you may get a busy
signal, reorder tone or howler tone - making it impossible for the others to
continue the conference.
Forum says that they don't have that problem as long
as some audio is sent from the analog station port when a party hangs-up. They
said that most systems send out in-band signaling, which can be a dial tone,
reorder tone, howler or DTMF digit (usually an A or D tone). Their bridge is
smart enough to split the line and listen for audio on each individual channel
(not passing the audio to the other station ports in the conference, which would
drop all the stations).
The problem comes in when the station port is silent
when a party drops off, but the bridge may still drop off correctly a few
moments later when the phone company sends their howler tone (after a message to
hang-up the phone, which would interrupt the conference for a while).
WHY CONFERENCE CALLS DON'T WORK WELL ON 2 WIRE
This Bulletin applies to phone systems
using phone lines that have 2 wires. Phone lines
delivered digitally, like on a T1 / PRI or VoIP (without a
two wire ATA), probably
won't have the same problems with conference calls since those trunks
are actually 4 wires, with separate transmit and receive
Because regular phone lines have 2 wires, both transmit and
receive are on the same pair. That means that when you try to amplify
the lines enough to make a conference call sound decent you'll hear
squeal, ringing or feedback.
older systems have analog 4 Wire E&M trunks, which can be conferenced
without a problem since they also have separate transmit and receive
pairs, and won't cause feedback when amplified enough to make the
conference call sound OK. Not many of those types of lines left out
Can the phone
system manufacturers build "good" conferencing into their phone systems?
Yes. Do most do it? No.
conference calls have been a feature on phone systems for over 30 years,
and here we are making calls on our computers and through the Internet (and used-to fly to the moon),
you'd think the manufacturers would feel bad about including a feature
that obviously doesn't work (and hasn't worked for decades)?
personally use the Flash Button type conference using 3-Way Calling from the
phone company on our POTS lines every day. It always sounds great to all
parties. It even works well on our SIP trunks (which we use for outgoing - we
only use POTS lines for incoming calls).
conferences most companies have turned to one of the zillion conference
services that have sprung up. You can find tons of them on Google.
they used to be expensive, competition has forced prices down.
Since many use VoIP on their end, the quality is not the same between
providers. Try them out to see when you get, but you generally get what
you pay for.
There are two types of conference services:
setup the conference yourself by calling the parties, or telling them to
call a number at a certain time.
2. Pay more and have an operator do
the dirty work for you.
Setting up a conference by calling into a designated number
at a designated time can be intimidating for both the users and the guy
controlling the conference from his touch tone phone. Even so, it's
probably the best solution to multi-party conferences.
for many conference services (and built-into some VoIP phone systems) is recording the conference call