Qualcomm is urging U.S. trade regulators to reverse a judge’s ruling and ban the import of some Apple iPhones.

The company hopes of dealing Apple a blow before the two begin a major trial in mid-April in San Diego over Qualcomm’s patent licensing practices. Qualcomm is already applying pressure to Apple with smaller legal challenges ahead of that trial and has won partial iPhone sales bans in China and Germany against Apple, forcing the iPhone maker to ship only phones with Qualcomm chips to some markets.

However, Apple say it has found a software fix to avoid infringing on one of Qualcomm’s patents. Apple asked regulators to give it as much as six months to prove that the fix works. This means that
any possible ban on iPhone imports to the United States would be short-lived. Still, Qualcomm argues that the Intel-chipped phones should be banned while Apple deploys its fix.

Qualcomm brought a case against Apple at the U.S International Trade Commission in 2017 alleging that some iPhones violated Qualcomm patents. Qualcomm asked for an import ban on some older iPhone models containing Intel chips.

In September, an administrative law judge at the ITC found that Apple violated one of the patents in the case but declined to issue a ban, since it could harm competition in the modem chip market.

In December, ITC said it would review the Judge's decision and decide whether to uphold or reverse it by late March.