A classic joke about accordion players was printed in Herb Caen’s column in the San Francisco (CA) Chronicle, on March 22, 1993:
   
“Comedian Ronnie Schell at the Washbag Thurs. night, offering his definition of an optimist: ‘An accordion player with a beeper.’”
 
A riddle about an accordion player with a pager was posted on the newsgroup rec.music.makers.guitar.jazz on March 16, 1996:
   
Q: What do you call an accordion player with a page?
A: An optimist.
     
That is, no one is going to call an accordion player for booking a gig. The beeper/pager joke is technologically dated, but is still told about accordion players.
     
         
Wikipedia: Ronnie Schell     
Ronald Ralph Schell (born December 23, 1931) is an American actor, stand-up comedian, and voice actor. He appeared on the May 28, 1959, episode of the TV quiz program You Bet Your Life, hosted by Groucho Marx. Schell demonstrated a comic barrage of beatnik jive talk. As a stand-up comedian, he first developed his act at the world-famous hungry i nightclub in San Francisco, California. Schell is probably best known in his 1960s television role as Duke Slater in Gomer Pyle, U.S.M.C.
 
22 March 1993, San Francisco (CA) Chronicle, Herb Caen column, pg. B1, col. 1:
Comedian Ronnie Schell at the Washbag Thurs. night, offering his definition of an optimist: “An accordion player with a beeper.”
 
25 March 1993, The Daily Oklahoman (Oklahoma City, OK), “‘Arkansawyers’ Get New Label” by Argus Hamilton, pg. 2, col. 1:
He (Bill Clinton—ed.) meets the true definition of an optimist: An accordion player with a beeper.
 
Google Books
The Reader’s Digest
Volume 143, Issues 856-860
1993
Pg. 54:
Q: WHAT’S the definition of an optimist?
A: An accordion player with a beeper. —Ronnie Schell, quoted by Herb Caen in San Francisco Chronicle
 
28 April 1993, Chicago (IL) Tribune, “Inc.” by O’Malley & Collin, sec. 1, pg. 22, col. 1:
Tim Kazurinsky’s definition of an optimist: an accordion player with a beeper.
 
27 May 1993, Brunswick (GA) News, “Carson Still King, Even in Daytime” (AP), pg. 5C, col. 4:
Between jokes Monday, (Johnny—ed.) Carson said the expected things about how much fun he had had during his amazing career and how he had faith in television’s future. “Of course,” he quipped, “in the entertainment business an optimist is an accordion player with a beeper.”
 
Google Groups: rec.arts.tv.soaps
GL: TGIF 7/9 Update
Marni
7/10/93
(...)   
David: “Do you know what the definition of an optimist is? An accordion player with a beeper.”  Stavros: “I don’t get it.”
 
Google Groups: rec.music.makers.guitar.jazz
Guitarit/musician jokes needed
Lawson G. Stone
3/16/96
(...)
What do you call an accordion player with a page? An optimist.
 
Newsweek
LADY OF PAIN
BY NEWSWEEK STAFF ON 6/9/96 AT 8:00 PM EDT
PITY THE POOR ACCORDION. DESPITE an illustrious and astonishingly varied history, it is the one musical instrument that is guaranteed to make people roll their eyes. Sometimes it seems as if it had been invented less to make music than to serve as the butt of jokes. (What’s the show-business definition of an optimist? An accordion player with a beeper.)
 
Google Groups: aus.jokes
music
Miss Kitty
4/5/98
(...)
Q: What do you call an accordion player with a beeper?
A: An optimist.
 
Google Books
Nursing a Sense of Humor
By Pamela Brede Minden
Ph. D. University of Wisconsin-Madison
1999    
Pg. 380:
He goes on, “What do you call an accordion player with a beeper?” l have no idea. “An optimist.”
 
22 August 1999, The Press Democrat (Santa Rosa, CA), “Cotati squeezes most out of accordion fest” by George Lauer, pg. 10:
What do you call an accordion player with a pager?
An optimist.
         
Google Groups: alt.music.weird-al
Accordion Jokes and Humor
Strawberry
7/7/00
(...)
Q* What do you call an accordion player with a pager?
A* An optimist.
 
Google Books
The Best Musicians’ Jokes
By Bruno Kassel and Carlo May
Pacific, MO: Mel Bay Productions, Inc.
2005
Pg. 85:
What do you call an accordion player with a beeper?
An optimist.
 
16 February 2006, Roanoke (VA) Times, “Roanoke.com,” pg. IS3:
“What do you call an accordion player with a beeper?” “An optimist.” .
         
Twitter
Glen Campbell
@glenc
What do you call an accordion player with a pager? An optimist.
2:07 AM - 13 Mar 2009
 
Reddit—Jokes
Posted by u/mivaldes June 16, 2017
What do you call an accordion player with a pager?
An optimist.
   
Twitter 
Watt L. Black, Jr.
@WattBlack
Replying to @nilslofgren @JohnBerman @AliRogin
The Uke is finally getting it’s due, eventually the accordion will, too - and the old “what do you call an accordion player with a beeper? An optimist” joke will be out of date for reasons other than the beeper reference.
6:30 PM - 10 Jul 2019
 
Next Avenue
The Accordion Is Back! Give It a Hug!
This versatile and beloved instrument is enjoying a renaissance
By Rosie Wolf Williams July 17, 2019
What do you call an accordion player with a pager?  An optimist.
 
The old joke aside, the funny thing about the accordion is that this offbeat musical instrument remains a beloved part of our lives.