Permanent signal

Permanent Signal (PS) in US telephony jargon, or Permanent Loop in British usage, is a condition in which a POTS line is off-hook without connection for an extended period of time. This is indicated in modern switches by the silent termination after the off hook tone times out and the telephone exchange computer puts the telephone line on its High & Wet list or Wetlist. In older switches, however, a Permanent Signal Holding Trunk (PSHT) would play either a howler tone or a 480/500 Hz high tone (which would subsequently bleed into adjacent lines via crosstalk). Howler tone is a tone of increasing intensity that is intended to alert telephone users to the fact that the receiver has been left off the hook without being connected in a call.

Permanent signal can also describe the state of a trunk that is seized but has not been dialed upon, if it remains in a busy condition (sometimes alerting with reorder).

In most mid-20th-century switching equipment, a permanent signal would tie up a junctor circuit, diminishing the ability of the switch to handle outgoing calls. When flooded cables or other conditions made this a real problem, switch staff would open the cable, or paper the off-normal contacts of the crossbar switch, or block the line relay from operating. These methods had the disadvantage of blocking all outgoing calls from that line until it was manually cleared. Manufacturers also sold devices that monitored the talk wires and held up the cutoff relay or crossbar hold magnet until the condition cleared. Some crossbar line circuit designs had a park condition allowing the line circuit itself to monitor the line.

Permanent Signal (album)

Permanent Signal is the second studio album by American musician Porcelain Raft. It was released in August 2013 under Secretly Canadian.

Permanent Signal was recorded at the end of 2012 with all new equipment and help from Jonny Rogoff (Yuck) on drums, Darby Cicci (Antlers) on bass and Gaspar Claus (collaborator of Sufjan Stevens and The National) on cello. The title is meant to evoke a sense of loneliness through the symbolism of a phone-line without connection. Remiddi articulated feelings of disconnectedness when discussing the record and life on-tour. "In a way, growing up in Italy, then living for 12 years in London, and now two and a half years in New York, made me realize that I have some dear friends I rarely see," explains Remiddi. "I was touring almost non-stop for eight months and I started having these imaginary conversations in my head with people I wanted to communicate with, but for one reason or another it couldn't happen. This is where the album title came from: the idea of a signal that says the line is off."