Chipmaker Qualcomm has appealed against a ban that could block over four million phones from entering the US market. The ban was announced by the International Trade Commission and is the result of a long running patent dispute.
The ITC said that it was banning the import of phones which use Qualcomm chips that it said infringe a patent held by Broadcom. Broadcom has been in a long running dispute with Qualcomm over the chips, while Qualcomm has also been engaged in a protracted patent fight with phone maker Nokia.
Nokia, the biggest mobile phone maker in the world, filed a new counter-suit against Qualcomm in a Texas court, alleging that that company's technology infringes a Nokia patent.
The ITC decision comes after an ITC administrative judge ruled last year that Qualcomm had violated a Broadcom patent covering power-saving in a phone's battery.
Qualcomm said that it has now filed a request for a stay on the import ban, which took effect on 7th June.
Broadcom had filed a suit with the ITC asking for a ban on all high speed wireless phones carrying Qualcomm chips. The judge agreed that one patent had been infringed but rejected two of Broadcom's claims.
The ITC is a government agency and its decisions can be appealed through the court system.
Research firm iSuppli Corp has said that the ban could affect 11 phone models totalling some 4.2 million phones.
Nokia's counter-suit follows a patent infringement suit filed by Qualcomm against Nokia in April alleging that Nokia's software download technology infringed its patents.
Nokia said that not only does it believe that its technology does not infringe the patents, but that the patents are invalid because others published or patented the technology first.
The ITC ban and Nokia counter-suit are the latest twists in a series of lengthy legal battles over mobile phone patents.
In 2005 Nokia, Broadcom and others complained to the European Commission that Qualcomm had fallen foul of antitrust regulations in relation to patents for 3G technology.
A week later Qualcomm sued Nokia over 12 alleged patent violations. A patent agreement between the two firms ran out in April this year and has not been replaced by another agreement.