Historical clue formulations

• 4 letters — 2014-09-21
• Telephone trio — 2012-01-06
• 4 on a phone — 2011-09-11
• 4 letters — 2009-12-04
• 4 on a telephone — 2009-04-28
• 4, on a phone — 2008-06-15
• 4, on a phone — 2008-05-21
• 4, on a keypad — 2008-04-29
• 4 on a fax machine — 2004-08-15
• Phone trio — 2002-05-03
• 4, on a phone — 1998-05-27
• Phone trio — 1998-01-11
• Four, on the phone — 1997-08-21
• Touch-tone 4 — 1997-07-22
• Alphabet trio — 1995-02-24