Ericsson, an early pioneer in cellphone technology, has upped the ante in a patent dispute with Apple by asking the U.S. International Trade Commission to block the import of iPhones into the country.

Ericsson owns patents to a number of fundamental technologies used in all cellphones, including LTE, and Apple had been paying royalties for these up until mid-January when the license fell due for renewal, reports Bloomberg … 

Apple had been paying royalties to Stockholm-based Ericsson before a license expired in mid-January. When talks over renewal failed, the companies sued each other, seeking court rulings on whether Ericsson’s royalty demands on fundamental technology were fair and reasonable.

The royalty payment is on a per-phone basis, with Re/code reporting that the total sum Ericsson wanted would range from $250-750M per year. Apple took Ericsson to court, arguing that the company is not infringing the patents and that the royalty should be based on the relevant component rather than a percentage of the handset cost. Ericsson countersued, asking a court to decide the appropriate royalty.

It total, seven lawsuits have also been filed as part of the dispute, two of which are likely to be put on hold until the outcome of the ITC complaint.

The ITC did previously apply a limited ban to the iPhone 3GS, iPhone 4 and 3G iPads over a patent claim by Samsung, but this was overturned by President Obama. Samsung was unsuccessful in requesting a similar veto on its own ITC ban.