Contact an attorney.
Some cases are worth fighting while many others can be resolved for a relatively small amount or no payment which is often less than it would cost to respond in court. If you contact an attorney early enough, it is possible in some cases to settle bit-torrent and file sharing cases without revealing your actual identity. This cannot be done once your ISP answers the subpoena.
If your attorney is representing multiple defendants in the same case on the same issue, depending on the circumstances, fees and expenses can be split amongst multiple defendants.
If you do not timely respond your identity will likely be revealed and lawsuit filed against you.
If you fail to respond to a lawsuit a default and final judgment may be entered against you.
It is important to consult with and retain an attorney to properly document any settlement, and defend you in a copyright infringement lawsuit.
Call attorney Peter A. Koziol, Esq. at 561-235-0725 to learn about quashing subpoenas.