Two corporate titans, one in the software world, the other in the world of telecommunications, will do battle in the U.S. Supreme Court this month over the reach of domestic patent law beyond the borders of the United States.

The financial stakes for Microsoft Corp. and AT&T Inc., in particular, and for the software industry in general, are huge, but the ramifications of a Supreme Court ruling most likely will be felt far beyond the software industry, according to patent litigators and others. Microsoft v. AT&T, No. 05-1056.