NO CARRIER
![Current use: no carrier status message shown in widgets of a PC-BSD 10.1.2 network manager (running on MATE). Three network interface widgets (2 ethernet and 1 WiFi) showing two network interfaces being up, one being down with no cable plugged in (hence:](/Images/godic/202501/29/No_carrier_PC-BSD1325.png")
NO CARRIER (capitalized) is a text message transmitted from a modem to its attached device (typically a computer), indicating the modem is not (or no longer) connected to a remote system.
NO CARRIER is a response message that is defined in the Hayes command set. Due to the popularity of Hayes modems during the heyday of dial-up connectivity, most other modem manufacturers supported the Hayes command set. For this reason, the NO CARRIER message was ubiquitously understood to mean that one was no longer connected to a remote system.