A German seller telephones an American buyer and says "I will sell you 150 hand-held organizers at $50 each. This offer is open for ten days; all acceptances must be in writing."
1) The next day, the seller telephones the buyer and says, "Sorry, I have to withdraw the offer as I am having inventory problems." The buyer replies, "I hereby accept your offer. As you telephoned me yesterday with this offer, the offer received by me became effective and by its own terms, the offer was irrevocable for a period of ten days. The acceptance was within the ten days you held the offer open so a contract has been formed." Was the seller's second phone call can attempt withdrawal or revocation? see Articles 15 and 16. Was the buyer's oral acceptance effective or must the buyer responding in writing? See article 11. Neither Germany nor the United States has made a declaration under Articles 12 and 96. see also article 6.
2) Suppose that after receiving the initial telephone call in which the seller makes the offer, the buyer calls back the same day and says, "Sorry, the price is too high so I can't accept your offer." The next day, the buyer alls the seller and says, "I talked it over with the finance department and it's a go. We accept the offer and I am having a written acceptance delivered to you within the hour." The seller says, "Sorry, but you already rejected the offer yesterday so no deal." The buyer says, "You promised to hold the offer open for ten days and my written acceptance will be received by you within this period." Is there a contract? see Article 17