This is a landmark contract law case that distinguished "instantaneous forms of communication" (like telephone and Telex) from the "postal rule." It established that for instantaneous communications, a contract is only formed when and where the acceptance is actually received by the offeror. 

• The Parties: The plaintiffs (Entores) were an English company based in London. The defendants (Miles Far East Corporation) were an American corporation with agents based in Amsterdam.

• The Communication: Both parties had Telex machines (teleprinters), which allowed users to type a message in one country and have it instantly printed in another.

• The Offer: On September 8, 1954, the plaintiffs in London sent a counter-offer by Telex to the defendants' agents in Amsterdam to buy 100 tons of copper cathodes.

• The Acceptance: On September 10, 1954, the agents in Amsterdam sent an acceptance by Telex, which was received on the plaintiffs' machine in London.

• The Dispute: The plaintiffs alleged a breach of contract and sought to serve a writ on the defendants in New York. Under the court rules, they could only do this if the contract was "made within the jurisdiction" (i.e., in London).

• The Argument: The defendants argued that the "postal rule" should apply, meaning the contract was made in Amsterdam the moment the acceptance was typed (dispatched).

• Does the "postal rule" (where acceptance is effective upon posting) apply to instantaneous communications like Telex?.

• Was the contract made in Amsterdam (where the acceptance was sent) or London (where it was received)?.

The Court of Appeal dismissed the appeal, ruling in favor of the plaintiffs. The contract was made in London, so the writ could be served out of the jurisdiction. 

• Instantaneous Communication Rule: The postal rule is an exception based on convenience for mail; it does not apply to instantaneous communications like telephone or Telex.

• Requirement of Communication: For instantaneous methods, the general rule applies: there is no binding contract until the acceptance is actually notified to (received by) the offeror.

• Place of Formation: Because the contract is not complete until the offeror receives the acceptance, the contract is legally formed at the place where the acceptance is received. In this case, the acceptance was received in London, so the contract was made in London.

• Analogy: Denning L.J. used the analogy of two people talking across a river or on the telephone. If a line goes dead or a shout is drowned out by an aircraft, there is no contract because the offeror did not hear the acceptance. The acceptor must repeat the message until it is received.