Around 1930, message routing was the last great barrier to full automation. Large telegraphy providers began to develop systems that used telephone-like rotary dialling to connect teletype machines. These machines were called "TELEX". TELEX is a system for tranmission of text messages. For this TELEX system there is a fixed network on shore connecting all the TELEX terminals. Between this network there is also a connection possible via the LES's to the Inmarsat system or via Maritime Coast radiostations to Wireless MF/HF radio TELEX terminal connected to the MF/HF radio equipment on board.
When you send a TELEX you should select 'new TELEX' in the file menu of the menu bar. When transmitting this telex you should mark this in the address book as message type TELEX.

Practise on the Inmarsat C simulator

Composing and sending a TELEX message:

• Select 'File' in the Menubar on the top of the screen by using the arrow keys followed by 'Enter'.
• Select 'New TELEX' by using the arrow keys followed by 'Enter'.
• Now the cursor is blinking on the top of the Text field, text can be added by typing it in on the keyboard.
• When the text has been entered you can transmit it immediately (Alt,T combination to enter the transmit menu) or save it (Alt,F,S combination to enter the file save menu).
• Go to the address book by touching the spacebar.
• Select an address using the arrow keys and press 'Enter' or add a new one to the address book so as to select character size (5,7 or 8 bit) e.g. when you choose 5 bit, each character (letter, number etc. consists of 5 bits). In this 5-bit character set not all special characters are available. 5 bit is of course the cheapest option because the calculation of the cost will be ...$/256 bits. When sending a telex to a land user of the TELEX system, it is important to select a 5-bit code because the land-based TELEX system uses the 5 bit character set.
• Go to Land Station using the arrow buttons and touch the 'Space Bar' and then select a Land Earth Station using the arrow keys and confirm your choice by pressing 'Enter'.
• Go to '[X] Text in editor ' using the arrow keys (by-pass this item when you wish to send your text message from the screen), touching the 'space bar' in this position the mark showing '[ ] Text in editor ' and 'File' will be removed: below this field this option can be used to transmit a saved file.
  
• Go to the priority menu by using the arrow keys and select the priority of message (Routine, Non Urgent or Distress) by using the 'space bar'.
  
• Go to the request confirmation by using the arrow keys and decide if you wish to have a delivery confimation request, this could be selected by using the 'space bar'.
• Go to Print by using the arrow keys and decide if you wish to print the file, this could be selected by using the 'space bar'.
• Go to immediate transmission by using the arrow keys and decide if you wish to have a direct transmission, this could be selected by using the 'space bar' .
• Go to Send using the arrow keys and press 'enter' (or enter password if protected)
• The TELEX will now be transmitted to the LES and after the successful delivery you will get a confirmation, if you've chosen this option.
• During the transmission of the message the indication light 'Send' on the transceiver is blinking and the status field on the screen shows 'Sending'.

The process of message delivery can be monitored in the 'transmit log', which can be found under 'logs' in the 'menu bar'. In this 'transmit log' you can also find details of the message such as the total number of characters or quantity of bits the message contains.