Apple (NASDAQ:AAPL) proposed a reciprocal agreement regarding cross-licensing patents to Samsung in the months before their August patent trial in San Jose, California, according to a court filing. However, the two smartphone rivals failed to agree on terms acceptable to both and talks eventually broke down.

Apple’s intellectual-property licensing director, Boris Teskler, sent the details of the proposed deal to his counterpart at Samsung, Seongwoo Kim, in a three-page letter on April 30, CNET said. Teskler offered to license to Samsung its Universal Mobile Telecommunications System patents on nondiscriminatory FRAND terms and estimated the payment to be 33 cents per device. That was on the condition that Samsung “reciprocally [agreed] to this same, common royalty base, and same methodological approach to royalty rate, in licensing its declared-essential patents to Apple.” The iPhone maker proposed that the rate apply to all Samsung units that it had not otherwise licensed and vice versa.

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Apple asked for a reply by May 7, and it’s not clear if Samsung responded to the offer. In the same letter, Apple also challenged Samsung to provide evidence that it had ever received its requested 2.4 percent average selling price terms during negotiations.

“You have previously suggested that you cannot share license-terms information because of confidentiality agreements,” the letter said. “But Samsung’s own valuations of its own patents, as conveyed to other companies, constitute information that is within Samsung’s sole control. Again, can you provide any evidence that Samsung has ever negotiated a license based on a proposal that Samsung’s declared-essential UMTS patents be valued at 2.4 percent of [average selling price]?”

Apple had also offered a patent licensing deal to Samsung in 2010 at the rate of $30 per smartphone and $40 per tablet. The latest letter was made public after U.S. District Court Judge Lucy Koh rejected the two companies’ request to keep the case documents sealed.

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