Includes postal services and voice mail.
- Postal services - the services used to transmit physical objects and tangible letters across space
This category has only the following subcategory.
Pages in category "Message systems"
The following 4 pages are in this category, out of 4 total.
Media in category "Message systems"
The following 2 files are in this category, out of 2 total.
- Fig05-SiemensKarolusFacsimileSystem1927 0622.jpg 1,731 × 2,170; 584 KB
- Message Systems Morse code in British signal exchange Somme 1916.jpg 766 × 599; 74 KB