Genband has offered to pay less than $143 million for unit.
Nortel Networks Corp. disagrees with Genband Inc. over the final price tag on a former Nortel division that makes network equipment for phone calls over the Internet.
The announced price of $182 million on Genband's court-approved acquisition of Nortel's voice-over-Internet-protocol business was subject to adjustment under the sale deal approved by courts in the U.S. and Canada.
Nortel has raised about $3.2 billion by bankruptcy sales of its operating businesses as it seeks to raise cash for creditors. The Canadian company has yet to say whether it will reorganize as a technology licensing business or liquidate its patent portfolio and go out of business.
In the dispute over the VoIP unit sale, Nortel says Genband is shaving too much off the price, offering to pay less than $143 million instead of the $179.5 million Nortel wants.
Genband, of Plano, Texas, filed papers Thursday with the U.S. Bankruptcy Court in Wilmington, Del., asking that the dispute be sent to arbitration.
Nortel, of Toronto, filed for protection from creditors in the U.S., Canada and elsewhere in January 2009. By June of that year, it had scrapped the idea of reorganizing its telecommunications equipment manufacturing business to focus on asset sales. Nortel filed a skeletal Chapter 11 plan, one that leaves open the question of what will become of intellectual property worth an estimated $1 billion.