Preface/Introduction
A powerful telephone traffic analysis program, can help determine the right number of telephone lines, trunks/channels.

Efficient telecommunications requires enough lines to carry desired calls/sessions. The telecommunications industry has generally planned for enough lines to provide a P.01 grade of service (GOS), which means that one caller out of 100 will be blocked (receive a busy signal) on the first call attempt during the busiest hour (within a specified period, usually a day). Of course, with a P.01 GOS far fewer busy signals will be encountered during less-busy hours.

P.01 GOS is ideal for many circumstances. But if more than 1% busy signals is acceptable, fewer lines will be needed. And assurance of fewer busy signals will require more lines.

Traffic Concepts

uses queuing theory, a statistical method for predicting service levels within a system that provides a service of random duration to users demanding service at random times.

Traffic formulas and tables found in books require that the total amount of offered traffic be known and expressed in Erlangs in order to calculate the grade of service for various numbers of servers (e.g., lines, trunks/channels). However, in most real-world situations, available data usually describe carried, not offered traffic, and are rarely expressed in Erlangs.

overcomes two of these deficiencies by calculating accurately using carried traffic and busy-hour hours (Erlangs), minutes or CCS (100-second units) as direct inputs. And it represents GOS as a percentage, rather than a decimal (i.e., P.0100 = 1.00%). (The user must determine the busy-hour hours, minutes, or CCS to be entered.)

Definitions

Blocked Calls/Overflow - attempted (offered) calling that received a busy signal/condition.

Calls Cleared - blocked calling that is automatically routed to other line/trunks/channels, or from callers who immediately use other means to make the call.

Carried Traffic - the volume of calling completed between calling and called parties within a given period of time.

CCS - 100 call seconds; one hour = 36 CCS.

Erlang B - the calculation model used in , is ideal for use with situations wherein calls will be "cleared," which includes most outgoing calling.

Erlangs - total traffic, in hours, during the busiest hour.

Grade Of Service - the percentage of offered calling that will be expected to receive a busy signal/condition on the first call attempt during the busiest hour (within a specified period, usually a day).

Offered Traffic - the volume of calling placed within a given period, including calls that received a busy signal/condition.

Servers - telecommunications lines, trunks, channels, etc.

Program Limits
While you may see answers to calculations that exceed the following, entries to data fields are limited to these maximums:

Number of Servers: 100

Offered Traffic: 100 hours, or 6000 minutes, or 3600 CCS

Carried Traffic: 70 hours, or 4,200 minutes, or 2,520 CCS

Overflow: 20 hours

Calls Blocked: 20%

How To Use

Select (click on) busy-hour units of calling/traffic - hours, minutes or
CCS.

1. Two data factors must be entered; enter corresponding numbers (e.g., 1 and 3 indicates that you will enter the number of lines/trunks and the amount of carried traffic.
2. Click on "Calculate." Calculated values for the other three factors will appear.
3. If additional calculations are desired, repeat steps 2-4. It is not necessary to clear values before entering numbers for a new calculation.
4. Values from any calculation can be saved for viewing with new calculations by clicking on "Save Values" before starting a new round of data entry.
5. All entries and values can be cleared by clicking on "Clear Values."
6. Exit at any time by clicking on the X at the upper right corner.
   (Suggestion; provide an "exit" button below "calculate" at the lower right, which then returns to first screen to allow viewing instructions, or complete exit.)

How To Estimate Busy Hour
If you don't have direct busy-hour data, you can estimate the busy hour using the following formula:

Hours of Daytime Traffic (adjusted as appropriate)
Busy Hour
----------------------------------------------------------------------- X
bh Factor
                   Number of
Business Days in the Billing Period
Normal Daily Facility Use              Usage During Busiest Hour

4	Hours	0.34	(34%)
5	Hours	0.27	(27%)
6	Hours	0.23	(23%)
7	Hours	0.19	(19%)
8	Hours	0.17	(17%)
12	Hours	0.14	(14%)
24	Hours	0.12	(12%) Click the graphic below to use Traf

Use the following decimals for bh factor:

Questions? contact us and we'll help you use Traf...