Most CPE (Customer Premise Equipment) systems today reside in
Wintel PCs equipped with special ISA and/or PCI board-level products
and their accompanying DSP processors, although some systems are
founded on firmware within proprietary systems and on circuit
boards within a business telephone system.
The capacity of the voicemail system is expressed by two primary
variables: the number of ports; and the amount of storage time
for announcements and caller messages.
Most voicemail systems connect to the telephone system (the platform
that actually switches the calls) using analog ports (the same
type of ports used for basic single-line telephones). Some are
available to connect using a digital connection — a connection
wherein the voicemail essentially mimics a proprietary digital
PBX telephone for advanced signaling between the adjunct processor
and the switch.
Voicemail systems are usually sold in two-, four- or eight-port
increments. These days, they usually come with 100 hours of storage
at minimum, although there are some very cost-effective solutions
that cut down on system storage as they cut down on overall system
price.
Message Forward / Rewind / Pause-Resume.
Not unlike accessing a tape recorder.
AMIS Networking.
A standard that lets different voicemail systems from different
vendors pass messages back and forth.
Multiple greetings per subscriber.
A decent voicemail system should let each user in the system
toggle between at least two greetings — a standard one;
and an "away-from-the-office" one.
Message forwarding.
Users can forward messages to other subscribers' mailboxes.
Broadcast Messaging.
Users can forward to multiple mailboxes simultaneously.
Distribution groups.
Users can set up pre-defined broadcast-messaging groups.
Messages Appending.
Lets people record a header onto a received message and forward
it other users.
Messaging Waiting Indication.
On the phone through stutter dialtone and/or a message-waiting
lamp.
Pager and Outdialing Notification.
For remote message notification.
Private Messaging.
Wherein callers can enter special PINs to get secret messages
out of subscriber mailboxes.
Fax integration.
Wherein subscribers' mailboxes can handle fax as well as
stored voice.
Voicemail Scan.
This lets users get into voicemail queue, hit a DTMF command
and hear just the first five seconds of each voicemail message
until they hit something they want to really listen to, whereupon
they hit another DTMF and the feature is turned off and plays
that message in its entirety.
Auto Callback Messengers.
If the system captures CLID and associates it with a message,
subscribers can hit a DTMF or callback icon and speed-dial
the number.
Auto Re-Queue.
After an automatic callback from the message stack, this
lets subscribers hit a touchtone sequence to drop back where
they left off in their message queue — ala AltiGen's
excellent "Boomerang" feature... not really needed
with visual voice mail GUI, but great for remote message or
plain TUI access.
Visual Voicemail.
This implies that the voicemail system has been networked
on a LAN or WAN and provides a desktop interface into its
use and control.
Message Monitoring.
With visual voicemail, from the messaging GUI, you can dump
someone into voicemail and listen to what they're saying.
If you like it, then you can pull the person out.
Internet Messaging.
The platform provides browser access to messaging mailboxes
and voice streaming to remote web clients.
Make sure the system fulfills your line needs.
To figure out what your line needs are, you have to become
familiar with one of the magic words in telephone traffic
analysis — the "Erlang."
The Erlang telephone traffic models are based on work performed
years ago by a Danish guy named — you guessed it —
Mr. Erlang. The statistical models he created are now commonly
used to estimate the performance of telecom systems, including
PBXs, central-office equipment, voicemail and IVR systems.
The basic idea behind these traffic models is not difficult
to grasp. We all want telecom systems to handle calls without
"blocking" — that is, without callers receiving
a busy signal.
To ensure non-blocking performance, the first thing you need
to know is how much traffic (i.e. number of calls of a known
length) will occur during the busiest hour of telecom system
use.
Then you need to know what is an acceptable percentage for
callers who will get a busy signal (blocking factor). Using
the Erlang telephone traffic models, if you know the busy
hour traffic and the blocking factor, you can solve the line-requirement
riddle.
It gets more complicated. We recommend going to Westbay Engineers'
www.erlang.com site. There you'll find a free Java-based online
traffic calculator for Erlang B calculations that provides
results for up to 180 phone lines. What's more, for $80 you
can download a Windows-based calculator for your PC or laptop
that does more advanced Erlang calculations.
Look for very easy administration.
Almost every voicemail system, even services, are administered
by end users. You definitely don't want this kind of system
to dominate time. It should be easy to change the system.
And you'll have to always change a voicemail system as people
move, people come, people go, etc.
Look for proper phone-system installation and integration.
Perhaps the most important thing to look for in an "adjunct"
voicemail system (one that attaches to a separate business
phone system) is how well it integrates with the phone system
in question.
On the integration front, you want a system that interprets
follow-on ID and auto-login DTMF information and picks up
on call disconnects by getting positive disconnect signals
from the phone system (so ports aren't left hanging). In order
to accomplish this, the voicemail system must communicate
properly with the phone system — a task that's not trivial,
considering that phone systems operate and signal differently
from manufacturer to manufacturer.
The best form of voicemail integration still involves something
called "digital phone set emulation".
This technology is provided either by specialized PC boards
or external boxes. Essentially, they appear to the telephone
system switch as digital phone sets and, thus, receive instructions
in the switch's own proprietary language in separate digital
channels. Then they turn over all that information, usually
via an out-of-band SMDI interface, to the voicemail / auto
attendant / audiotext app processor.
It's important to note that when voicemail vendors say their
product integrates with 60 different switches, they're usually
not referring to a specific digital-emulation mode; they're
referring to analog inband signaling.
Here, the voice-processing board in their system is simply
listening for and barking back the DTMF tones a switch wants
to hear to transfer/make/disconnect a call or that a switch
makes to pass follow-on IDs or light message-waiting lamps.
This type of signalling takes up a voicemail port, is subject
to misinterpretation across the board and, because the tones
are literally audible, may annoy or confuse callers if tone
clamping is not performed.
Overall, you should pay keen attention to how the vendor
treats this crucial "integration" topic. If they
gloss over it, you could be headed for trouble. Instead, look
for vendors that provide: extensive documentation on phone-system
integration; an extensive drop-down phone-system model list
in their installation software; special utilities for tweaking
phone-system integration; and specific platforms that include
specialized integration technology from vendors such as VTG
and Calista.
Y2K compliance.
There is fear in the industry that come the new year, every
new voicemail message will be considered out of date (after
all, who wants messages from the year 1900) and be auto deleted.
Voicemail vendors should be providing guarantees this won't
happen.
Suitable feature sets.
Every voicemail system, at a minimum, should provide the
following:
- Message Forward / Rewind / Pause-Resume;
- at least two greetings per subscriber;
- Broadcast Messaging and Pre-defined Distribution Lists;
- Message-Waiting-Lamp, Pager and Outdialing message notification;
- Messages Appending;
- Urgent Message Marking.
Advanced features we strongly recommend, include:
- Voicemail Scan. Again, this lets users get into voicemail
queue, hit a DTMF command and hear just the first five seconds
of each voicemail message until they hit something they
want to really listen to, whereupon they hit another DTMF
and the feature is turned off and plays that message in
its entirety.
- Auto Callback Messengers. If the system captures CLID
and associates it with a message, subscribers can hit a
DTMF or callback icon and speed-dial the number.
- Auto Re-Queue: After an automatic callback from the message
stack, this lets subscribers hit a touchtone sequence to
drop back where they left off in their message queue —
ala AltiGen's excellent "Boomerang" feature.
- Visual Voicemail and accompanying GUI management tool.
- Message Monitoring: Lets you dump people into voicemail
and listen to what they're saying. If you like what you're
hearing, you can pull people out of voicemail jail.
- Internet Messaging: The ability to access messaging mailboxes
from remote web clients is enticing.
The system should also provide modules for related media-processing
and call control applications, including:
- Audiotext: Information only media-processing "trees"
that callers access.
- Q&A Mailboxes: Automates caller polling, with answers
provided usually with touchtones.
- Fax Broadcasting and Fax-On-Demand.
The system needs to provide real-time status info.
It should show, at a minimum, real-time stats on Mailbox
Usage, Mailbox Status, System Capacity and Line Status.
