Digital Transmissions DTMF
Funnily enough, this means transmission of data. It usually refers to accessing services such as e-mail, faxes and connecting your laptop to the Internet or office network via your mobile phone.
Data transmission is the conveyance of any kind of information from one space to another. Historically this could be done by courier, a chain of bonfires or semaphores, and later by Morse code over copper wires.