When you are a caller

-- Hello? -- Is that John? -- Can I speak to John? -- May I speak to John? When you are a receiver -- This is John speaking, who's that? -- Who's speaking please? -- Who's calling please? When you ask the caller to wait -- One moment please. -- Just a minute please. -- Hold on please. -- Hang on please When you ask the caller to leave messages -- Can you leave the message? -- Can I take your message? -- Would you like to leave a message? -- Would you like him/her to call you back? When calling the wrong number -- I'm afraid you got the wrong number -- Sorry, I think you reach the wrong number When asking the receiver to transfer the line -- Can I have extension 1234 please? -- Could you please transfer the line to Mr. John please? When finish talking -- Nice talking to you -- Talk to you later

Screw up>Slang

Informal

Definition:

To make a major mistake. Completely mismanage or mishandle a situation

Example:

1) Tom screwed up the whole project, and now we're four weeks behind schedule.

Etymology:

This phrase comes from World War II US Army slang.

Definition:

One who makes mistakes regularly; a failure. (Usually written as 'screw-up' when used as a noun.)

Example:

1) Be careful when you're dealing with Charlie -- he's a real screw-up.

English idioms relating to

Afraid of one's own shadow

A person who is afraid of their own shadow is very nervous
  or easily frightened.
  "I've never seen anyone so easily scared - she's afraid of her
  own shadow."

Tongue-twisters

Which means:

noun a sequence of words, typically of an alliterative kind, that are difficult to pronounce quickly and correctly.