As telephone calls occur, information about the calls is sent to the PBXs
SMDR (Station Management Detail Recording) or CDR (Call Detail Record) port on the PBX. A typical legacy SMDR connection might be a serial port
operating at 9600 baud. Newer PBX SMDR ports might support a network connection.
Information about each call might be sent to the SMDR port as the call
progresses or when the call has completed. SMDR information typically provides
information such as when the call started, the duration of the call, the
telephone extension that handled the call and the telephone line on which the
call was made.
An example might look like:
Ext. Ln. Start Duration Dialed Type Account
100 01 2015-11-23 22:24 01:42 5551234 I 1466
101 01 2015-11-23 22:40 02:17 5551235 O
110 02 2015-11-23 22:48 42:04 I 1975
110 02 2015-11-23 22:06 02:42 I
Of course nearly every manufacturer does this a different way. Even different models
of the same PBX may have different SMDR output.
column order, different date format and additional columns of information that may
be available for the specific PBX. Some systems may not include the system date,
others may omit the year, some may include information about abandoned calls
others may include caller identification information.
VoIP PBXs and SMDR
Newer VoIP (Voice over Internet Protocol) PBXs have started making inroads
into the PBX market. To the casual user they look and operate like legacy
systems. Behind the scenes instead of telephone calls being sent over standard
telephone lines the information is sent as internet traffic.
These systems can provide the same sort of SMDR information as 'normal' PBX
systems though the manufactures of some VoIP systems provide more information
about the digital traffic such as the number of bytes of information transmitted
rather than information about the actual telephone call, for example, abandoned call
Some suppliers have forgotten that these things are PBXs.
Recording SMDR information
The simplest means of recording SMDR information, and perhaps the original
reason SMDR ports were made available on PBXs, is to connect the serial SMDR
port output to the input of a serial printer. As each call record is sent by the
PBX to its SMDR port it is printed in chronological order.
Instead of connecting the SMDR port to a printer, connecting it to a computer
and a terminal program the records can be displayed on a computer screen as they
happen and saved to a file for later analysis.
Connecting a computer to a PBX
PBXs typically offer one of two means of connecting to a PC; via serial or
via network cables.
A connection from a PBX to a PC via a serial cable usually requires that
the PC is installed close to your PBX, this is due to the maximum length a
serial cable can have and still operate. The maximum length of a serial cable at the most a few
tens of meters.
A connection from a PBX to a PC via a
network cable typically allows the PC to be located anywhere on your local area network.
Processing SMDR information
Once call accounting records are saved on a computer in a simple text format they can be opened in
any standard program for basic call analysis. Simple analysis of such things as the
extension with the most calls or the busiest time of the day can be performed
with some manual call record filtering in programs such as Microsoft Excel.
Performing further analysis and correctly handling SMDR formats provided by
different PBXs requires the use of a Call Accounting application.
Basic types of call accounting software
All call accounting software connects to your PBX and record call records as
they are received from your PBX. If the call accounting software is not running
the call records are usually lost. Some PBXs can store call accounting records
for a while before losing the records.
The simplest call accounting programs run on your computer when you are
logged in. If someone else logs into your computer the call accounting software
does not receive any records.
Slightly more advanced call accounting software runs in the background and does not
require someone to be logged into the computer for the call records to be
received - if the computer is switched on the software is running.
The latest call accounting software runs as a very small program on an
existing office computer and sends your encrypted call information via the
internet to a hosted call accounting system. An alternative version of this is
the call accounting application being installed as a black box that sends your
call records to a hosted call accounting system. A 'black box' is just a small
dedicated computer that just does this one job.
Why use call accounting software?
Having a call accounting package recording calls is all very well and good
but the whole point of a call accounting system is to run reports, discover what
type and how many of calls are being made with the goal of making money (or at
least spending less), for example:
- Recharge call costs to different cost centers or customers
- Determine if you are paying for unused telephone lines
- Determine if you have too few lines to answer customer calls
- Determine if you are missing customer calls outside business hours
- Improve customer service answer times, response times and reduce transfers
- Discover telephone misuse by staff or third parties
- Detect toll fraud by third parties making unauthorized use of your PBX
- Protect your employees by reporting on malicious calls
- Understand your business productivity
- Understand your communications systems
- Support legal and regulatory requirements
- Discover employees making expensive long distance, mobile, international
or premium service calls
- Discover employee loss of productivity by making many or long personal
Toll fraud is the unauthorized use of use of your telephone system usually by
people outside your business. The average toll fraud in Australia is currently
thought to be $78,000 AUD.
Third-parties find a way into your PBX via a normal telephone line or via an
internet connection. Once connected to your PBX unauthorized calls are then made
to destinations such as international or premium rate numbers.
The first most businesses know about their system being fraudulently used in
this fashion is when the monthly telephone bill arrives from their telephone
A toll fraud detection system available as an option with advanced call
accounting systems notifies you of fraudulent activity as it occurs.
Problems with classic call accounting systems
Having installed a call accounting system customers, after a while, discover problems:
System is slowing down
As calls are added to a call accounting system's database the database becomes larger
and slower to respond and run reports. Even logging in to the system can become slower.
All call accounting software uses a database of some sort (even those systems that
say 'no database' - where do you think the data is stored if not in a database?
And, yes, a flat text file is a database.).
To keep costs low, cheap or free database systems are used. Such databases provide
little or no database maintenance tools and as a consequence database performance
degrades over time.
The 'remedy' for a larger and slower database is to delete 'old' records. This is
a temporary 'fix' and prevents you running reports on 'old' calls. How do you run
a monthly or yearly comparison report when you've deleted older calls?
System is down
As many call accounting systems are installed in an out of the way place and
only accessed once a month to do a monthly report or when there has been a
complaint of misuse it is only when the system is needed is it discovered that
it is not working.
The reason the system is not working may be simple to fix but
by then a month's call records can be lost. System misuse cannot be traced,
legal or regulatory requirements may not have been met and if you plan to
recharge calls to third-parties you lose that income stream.
These are all real-world
examples of call accounting systems failing and why telephone dealers typically
hate call accounting software:
- The PBX is not sending SMDR information - a problem with the PBX or the
SMDR port on the PBX may result in the PBX not sending any SMDR information.
It may be possible to fix this problem by restarting the PBX otherwise a
telephone technician may be required to fix the problem.
- The PC is not running - the PC may have stopped and not restarted due to
any of the following; someone did 'the right thing' and turned off the
computer before going home, no one is logged into the computer, the wrong person
is logged into the computer, there is a floppy disk in the drive and the PC did
not restart, the PC tried to boot from a CD, DVD or USB key, the hard disk
in the computer has failed, the PC hard disk is full, a Windows update occurred and no one logged on, the machine is
off after a power glitch.
- The PC is not receiving call records from the PBX - the cable from the PBX
to the PC is unplugged; the PC was moved and the cable not reinstalled, someone
needed the communications port for their application, the PBX was upgraded and
the cable not reattached.
- The PC is missing! As stupid as it sounds that happens from reasons such
as robbery to
someone borrowing the 'unused' PC for another task.
- The call accounting software is missing - the PC on which the software was
running has been changed, updated or replaced and no one knew the program was
installed and being used.
- The date format is wrong - a call accounting system needs to know the
date format used by the PBX SMDR, for example DMY (day month year) or MDY (month day year). If the PBX date
format is changed and the call accounting configuration is not updated you
might suddenly find your records are not being saved. If the date format is
changed from DMY to MDY records for 06 April will be stored in the database
for 04 June, records for 13 April won't store at all as there is no month
The date format is often changed by users thinking they are just changing
the display on their own handset when in actual fact they're changing the
date format of the PBX. Some PBXs when reset or after a power fault will
default to MDY which may or may not be the same as the call accounting
system configuration. Once the date format has been corrected you will have
to tell your call accounting system to delete database records and reprocess
calls with the new date format.
- The database has died - all call accounting systems require a
database that can require maintenance to keep it running
efficiently. Once it has died a technician has to be called to reinstall the
application and install your daily backup.
- Having rebuilt your call accounting system you discover you have no
An organized business takes backups of its systems and sends those backup
tapes or disks to another location each day. A backup schedule requires at least 8
sets of backup media:
Backups are done each night and the backup tapes or disks are taken off-site
(out of the office) each day. Off-site backups may be as simple as assigning a
person at the office to change the tapes over each morning and take them home
and remember to bring in the next tape the next day.
- 4 backups - Monday, Tuesday, Wednesday, Thursday
- 4 weekly backups - Friday 1, Friday 2, Friday 3, Friday 4
You do that don't you? You've also got to do the same for your call
Logging into the system to run reports
Most call accounting systems allow one or more users to login to the system
on the call accounting PC but not from their own PC. Due to the type
of connection between the call accounting PC and the PBX the call accounting PC is often installed in an out of the way place that
someone has to log into once a week or month to run reports.
Some systems get
around this by running a terminal program on the call accounting machine so users can
login from another machine. This sort of solves the problem but often only one
person can login at a time and you can only do that from the office computer.
Larger call accounting systems require you to add extra software to other PCs
to run reports on other PCs in your office. If you want to run reports from a PC
outside your office you might be able to add an extra module to be able to run
reports by connecting remotely to your office computer.
These so called remote access or web access modules attempt to add remote
access to a legacy call accounting solution.
Multiple site (multiple office, multiple branch) call accounting
Usually call accounting systems log calls from a single PBX at a single
Some call accounting systems can be used as a multiple site call accounting
system by installing a full system at each office and nominating one office as
the head office. Each night all the branch offices call the head office and copy
call information between systems.
Most call accounting systems are not really designed for multiple users or to
process calls from multiple offices or multiple PBXs.
Hosted call accounting systems
A hosted system is a call accounting system that installs a very small
program on a computer at your office or installs a black box and transfers the encrypted telephone calls
to a dedicated call accounting data center.
Instead of the call accounting system requiring a dedicated PC, database,
ongoing maintenance and backups the data is stored offsite and all the modules
likely to fail are at the remote data center.
- Daily off-site backups are performed by data center staff
- Database maintenance and performance tuning performed by data center
- System upgrades are automatically performed
- You're always using the latest version of software, the same version as
- Multiple user accounts can be created
- Multiple sites are supported with no special changes to your system
- Access can be restricted to a department or region
- Access can be restricted to reporting only preventing administration
- You can log in from any computer, anywhere without installing special
- Designed from day zero to support multiple sites, multiple users,
multiple user types
- Designed from day zero to be a remotely accessed hosted call accounting
- Custom database columns
- Custom report layouts
- Custom emailed report schedule
- If your PBX or PC has problems you're automatically alerted by email or
- Supports legacy key systems and VoIP PBXs
- Call information sent encrypted to data center
- All access to system configuration and reports via secure SSL web
browser such as IE, Firefox
- Access from your Apple, Linux, Windows PC or mobile device
- Toll fraud detection and alerting included in the standard version