It is only two months old – but now the new digital marketplace for ad trading that has just been built by AT&T is announcing three new non-AT&T supply partners.

“Community”, the platform created by AT&T’s Xandr ad-tech unit, will support buying ads in content owned by A+E Networks, AMC Networks and Cheddar, Xandr announced.

Community debuted in May, a new marketplace allowing advertisers to place video ads in AT&T-wide brands and across different screen types. That includes WarnerMedia’s CNN, TNT, TBS, truTV, B/R Live, Otter Media and Warner Bros.

But the signs are that Xandr wants to expand the inventory available to ad buyers beyond the AT&T portfolio. It already claimed integration of inventory from VICE, Hearst Magazines, Newsy, Philo, Tubi and Xumo. The addition of A+E Networks, AMC Networks and Cheddar represents another step taken.

In a video interview with Beet.TV in June, Rick Welday, Xandr Media president, explained the strategy.

“Both buyers and publishers, sellers of advertising, are not happy with all of their options today,” he said. “There are a lot of challenges that they’re facing from brand safety to measurement to transparency.

“So we have been very pleased to pull together a marketplace that is a premium marketplace, that addresses those concerns, where an advertiser can feel more confident about what they’re getting for what they’re paying.”

Xandr says Community taps in to first-party insights from AT&T’s footprint, including 170 million consumer relationships, to help advertisers target audiences based on intent, interest and lifestyle attributes.

Applying those powers to third-party inventory means AT&T is starting to show how the platform part of its equation can fuel marketing services even outside of its own content operations.

Those ads can be bought across connected TV, because Xandr’s cross-screen addressable technology is integrated with its Community.