The Software Freedom Law Center has filed a lawsuit against Verizon for allegedly breaching the terms of the GNU General Public License through its FiOS fiber-optic Internet and television service.

Verizon distributes a wireless router made by Actiontec Electronics to customers of its FiOS service. That router uses BusyBox software to manage internet traffic, and under the terms of the GPL, Verizon has to provide access to the source code to people who use the device. But the company has failed to do so.

This marks the fourth time that the SFLC has filed a lawsuit on behalf of the two programmers who wrote BusyBox. Earlier this year, Monsoon Multimedia became the first company to be sued for a GPL violation, but the dispute was quickly settled out of court. Xterasys and High-Gain Antennas were also sued in November on behalf of the BusyBox developers for violations of the GPL.