What is a Telepen Barcode?

What are Telepen Barcodes

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In today’s digital age, the use of barcodes has become an integral part of our daily lives. With the advancement of technology, different types of barcodes have been developed to cater to different needs. 

One of the barcode types that have been widely used is the Telepen barcode. In this article, we will discuss what a Telepen barcode is, how it works, and why it is such an effective tool for data encoding.  

What are Telepen Barcodes?

Telepen barcode

The Telepen barcode is a one-dimensional barcode symbology developed in 1972 by George Sims of SB Electronic Systems Ltd, a United Kingdom-based electronic system company. Telepen is a continuous, variable-length barcode, meaning it does not have any limit to the number of characters that can be encoded.   

The Telepen barcode was designed to encode all lower full ASCII character set (without using shift characters and only two different widths) and to be highly reliable when printed by ordinary printers like inkjet and dot matrix. ASCII (American Standard Code for Information Interchange) is a specific standard used for encoding text in computers and devices. ASCII has a total of 128 characters that include letters, numbers, punctuation marks, and control characters. 

Telepen symbology was intended as a competitor to Code 128 (which uses four different element widths) and Code 93. However, it found its primary usage in universities and other academic libraries in the United Kingdom.

Telepen barcode has two variants, Standard and Compressed Numeric mode. The compressed numeric mode provides twice the density of the standard mode. This unique feature allows it to more efficiently encode data without sacrificing accuracy or reliability. Telepen barcode also allows one-time mode code switching between standard and compressed numeric mode. 

Telepen barcodes can encode a maximum of eight ASCII characters or 16 digits per inch of barcode length. Each character in the barcode takes up an equal amount of space, meaning that the length of the code will not change unless the data it contains changes. 

Why Do We Need Telepen Barcodes?

The Telepen barcode is an alphanumeric linear code that has a wide range of applications in different industries.

Telepen was initially widely used in the UK for universities and academic libraries to identify books without manual data entry. Later, the usage of Telepen expanded to many other sectors, including automotive manufacturing and military defence organisations, for item identification and tracking purposes.

How Does the Telepen Barcode Work?

Unlike most linear barcodes, the Telepen does not provide independent encodings for each character. Instead, it operates on a bitstream, a sequence of bits. Telepen can represent any bitstream with an even number of 0 bits and is used on ASCII bytes with even parity (an additional bit added to a string of binary code) to meet the requirement.

Telepen’s bitstream is divided into bits and blocks of form 01*0. This form means that the blocks begin and end with a 0 bit and have any number of 1 bits in between. This form is then encoded in the following manner. 

  • “1” – encoded as narrow bar-narrow space
  • “00” – encoded as wide bar-narrow space
  • “010” – encoded as wide bar-wide space

Alternatively, the leading “01” and trailing “10” are encoded as narrow bar-wide space, with the remaining 1 bits coded as mentioned above.

How to Identify a Telepen Barcode?

How to Identify a Telepen Barcode

Telepen barcodes are easily recognisable due to their unique structure. They always begin with a start character and end with a stop character with a different and distinguishable structure than other barcode symbology.   

Telepen’s start character always encodes ASCII _ (underscore). In the binary form, the bitstream of the start character is represented as “11111010.” This bitstream in the barcode is represented as five narrow bars and narrow space pairs followed by one wide bar and wide space pair.

Telepen’s stop character always encodes ASCII “z” character. In the binary form, the bitstream of the stop character is represented as “01011111.” This bitstream in the barcode is represented as one wide bar and wide space pair followed by five narrow bars and narrow space pairs. 

Telepen Numeric Barcode - A Variant of Telepen Codes

Four characteristics of Telepen Numeric Barcode

The Telepen barcode has a variant called Telepen Numeric barcode. 

The primary difference between the regular Telepen format and the numeric variant is that the numeric variant can encode double-density numeric values. This means that the numeric variant can store twice as many numerical characters with the same amount of space. As a result, more information can be stored in less space. 

The Telepen Numeric code encodes number digits from 0 to 9. The code starts with a start character, followed by the encoded data, and ends with a stop character. A check digit is also included, which is calculated using Modulo 127.

The main advantage of Telepen Numeric codes over standard Telepen codes is that they can encode more information in less space.

Anatomy of a Telepen Barcode

Detailed anatomy of a Telepen Barcode

Telepen bar codes consist of the following elements. 

  • Leading quiet zone
  • Start character 
  • Data characters
  • Check digit
  • Stop character
  • Trailing quiet zone

Start Character

The start character signals a barcode scanner indicating that a Telepen barcode is being read and marks the beginning of the bar code. 

The start character is composed of five alternating narrow bars and spaces, followed by one wide bar and space. It is encoded in binary as “01011111”, which in ASCII representation translates to the underscore character (_). 

Data Character Set

The data character set is the area that represents the actual data that is encoded in a Telepen barcode. This area is scanned by a barcode reader and decoded back into human-readable form.      

Telepen barcode symbology (standard) can encode all 128 ASCII characters (lowercase only) as binary data without a shift character. 

Telepen numeric code can encode all numeric digits (0 to 9).

Stop Character

The stop character signals a barcode scanner indicating that the barcode has been fully read and marks the ending of the barcode.    

The stop character consists of a wide bar and wide space pair, followed by five narrow bars and narrow spaces. It is encoded in binary as “11111010”, which translates to the “z” character in ASCII representation.  

The AIM specification for Telepen mandates using two additional start and stop character sets to indicate that the encoded Telepen symbol contains compressed numeric data.

Check Digit

The check digit is the last single digit used to validate and verify the accuracy of a barcode. It can be any number from 0 to 9 and is mathematically calculated using existing data characters. 

Telepan barcodes use Modulo 127 (mod 127) or Modulo 11 algorithm to generate a check digit.     

Quiet Zone

Quiet Zones are empty spaces on the margins of a barcode. They help barcode scanners identify the barcode symbol, ensuring higher scanning accuracy.

How to Get a Telepen Barcode Symbology?

Telepen barcodes can be created in two ways. 

  • Using free barcode generators 
  • Using label design and print software

There are numerous free barcode generators available online that allow users to generate unique bar codes in minutes. Enter the numeric digits for the barcode on one of these free generator websites, then click ‘generate’. 

Another alternative is to use a label design and printing software like Seagull Scintific’s BarTender Software.  

The BarTender Software is a great tool for designing and printing barcode labels. With advanced features, it makes the barcode printing processes faster, more efficient, and cost-effective. To learn more about BarTender, refer to our guide on understanding BarTender software.

At Triton Store, we offer BarTender software in four different editions – Starter Edition, Professional Edition, Automation Edition, Enterprise Edition, and now the new Cloud Edition. Our prices are unbeatable, so take advantage of this opportunity to choose the software that suits your needs. 

How to Design Telepen Barcodes? - Barcode Designing Rules

Designing barcodes and labels is an invaluable component of a successful barcoding operation. An effective barcode label should follow the best design practices to be reliable and accurate. Our guides on best practices for designing perfect labels and barcodes and common mistakes to avoid when designing barcodes will come in handy. 

When designing Telepen barcodes, it’s important to carefully consider three key factors: barcode size, quiet zones and barcode tolerances. By considering all of these, you’ll be able to create Telepen barcodes that are easy to read and accurate. 

Barcode Size

Each Telepen barcode should contain 16 modules, with each module representing the width of the narrowest bar (X-dimension) in the barcode. 

Telepen barcode contains four to eight bars and spaces, which can be either one or three modules wide. This allows for 8-bit data encoding, with even parity for added security.

Point on design rule of barcode size of the Telepen Barcode
Design rule of the quiet zones of Telepen Barcode

Quiet Zones

The size of the quiet zones in a Telepen barcode should measure 10X or 2.54 millimetres, whichever is more. The ‘X’ refers to the X-dimension, which is the width of the narrowest bar of the barcode.


For Telepen barcodes, the maximum deviation from the nominal width of a bar or space should not exceed 0.4X. 

For open system applications, the minimum value for X should be 0.0075 inches or 0.19 mm. 

For normal applications, the minimum value for X should be between 0.010 inches and 0.0125 inches (0.25 mm – 0.32 mm).

List of three points on design rules for Tolerance of Telepen Barcode

How to Print a Telepen Barcode? - Barcode Printing Best Practices

Appropriately printing Telepen barcodes is crucial for successful scanning. Follow these tips to ensure that your barcodes are printed correctly. 

  • Always format barcodes in pure black with a white background. If you need to use colour, ensure the barcode is dark and the background light. 
  • Ensure a white space (quiet zone) around the barcode is clear and free from any other elements.
  • Adjust your printer settings to the highest photo quality to get the best results. Alternatively, try adjusting the printing resolution and print speeds until you find a setting that consistently creates scannable barcodes.
  • Always inspect the printed Telepen barcode for any smudges, scratches, or defects that may impact its clarity and readability.

Besides following the above-mentioned printing rules, using the right device is also crucial when printing barcodes. The best device for the job is a top-notch thermal printer. 

Thermal printers are printing devices that use heat to create an image on print media. These printers provide superior precision and accuracy compared to other printing technologies. They do not require ink or toner and have fast print speeds making them ideal for large-scale printing.   

At the Triton Store, we offer a wide variety of thermal printers from respected brands like Honeywell, Zebra, and TSC. Our inventory includes various printer models, such as direct thermal printers, thermal transfer printers, barcode label printers, desktop printers, and industrial printers. We take pride in our comprehensive thermal printer selection and ensure that you will find the ideal solution for all your printing requirements.

We also offer a full range of print consumables to ensure that you have everything you need for your barcode printing operations. Our consumables are made to the highest standards and feature long-lasting print quality with superior adhesion. Our range of thermal printer consumables includes thermal transfer ribbons, thermal labels, thermal carton labels, thermal carcase tags, and food-compliant thermal inserts.

At the Triton Store, we guarantee top-quality products at competitive prices. If you have any questions or concerns, please feel free to reach us via the live chat widget below. Our customer support team will be happy to help you out!  

The Bottom Line

Telepen barcode is a unique and versatile barcode system that has found extensive applications in various sectors. Its ability to encode complex and lengthy data and compatibility with different barcode scanners makes it an efficient and cost-effective solution for inventory and data management. 

Understanding how the Telepen barcode system works and its advantages can help businesses make informed decisions when choosing a barcode system for their operations.

We hope this article has given you a thorough understanding of Telepen barcodes. Thanks for reading! 

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