3D Connexion 555-540-702 on-hook, outside call, outside line, paging, park, pickup, program, tone

on-hook	a telephone is on-hook when the handset is
	in its cradle, depressing the switchhook
	button.
outside call	call between a System 25 telephone and a
	telephone not connected to System 25.
	Outside calls are made over Central Office
	or other trunks and are signalled by two
	short rings.
outside line	a trunk (line) to the Central Office or other
	system. Outside lines may be accessed by
	dialing an access code.
PDC	(Personal Dial Code) extension number that
	is assigned to an individual, and is normally
	associated with the telephone at the
	individual’s desk.
paging	feature that allows you to access paging
	equipment from System 25 telephones.
park	feature like hold except that it allows you to
	answer the call from any telephone.
pickup	feature that allows you to answer a call that
	is ringing at another telephone.
program	ability to store a telephone number or
	account code so you can access it by dialing
	a code.
queueing tone	five short tones indicating that your request
	for callback has been confirmed.
recall	button on some telephones that may be
	pressed instead of the switchhook.
ringback tone	repeating on/off tone indicating that the
	number you dialed is ringing.
special ringback	one long tone followed by one short, dull
tone	tone indicating that the person you dialed is
	busy and has Call Waiting.

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