High court hears arguments via phone.

WASHINGTON » Chief Justice John G. Roberts Jr. played traffic cop. Justice Clarence Thomas asked his first questions in more than a year. Justice Sonia Sotomayor disappeared for a few moments, apparently having failed to unmute her phone.

On the whole, the Supreme Court’s first argument held by telephone went smoothly, with the justices asking short bursts of quick questions, one by one, in order of seniority, as the world, also for the first time, listened in.

The argument on Monday morning began with the traditional chant, “Oyez! Oyez! Oyez!” said by Pamela Talkin, the marshal of the court. But that was almost the only traditional thing about it.

Roberts asked the first questions and then called on his colleagues. When lawyers gave extended answers, he cut them off and identified the next justice whose turn it was to ask questions.

The issue before the court was whether an online hotel reservation company, Booking.com, may trademark its name. Generic terms cannot be trademarked, and all concerned agreed that “booking,” standing alone, was generic. The question for the justices was whether the addition of “.com” changed the analysis.

Several of the justices suggested that the answer was yes. Thomas asked how an internet domain name differed from an 800 phone number, noting that 1-800-PLUMBING is a registered trademark.

Other justices pursued his point.

“You can have a trademark that’s a telephone number,” said Justice Stephen G. Breyer. “So why can’t you have a trademark that’s a ‘.com’?”

In their Supreme Court brief, lawyers for Booking. com listed countless trademarks made up of generic terms followed by “.com” that had been registered by the government.

Supreme Court arguments typically last an hour. But Monday’s session went over by about 15 minutes, a consequence of the new format.