Nokia and AT&T have always had a strong relationship when it came to offering their devices in the United States offering exclusives such as the Lumia 920, 830, 1020, and 1520. With the sale of their device division to Microsoft in 2013, Nokia's relationship with AT&T passed to Microsoft, and it looks like they plan on keeping it a fairly strong one.
The Lumia 950, the smaller of the the two flagship devices announced today, will be going to AT&T in the United States. Historically speaking, AT&T has been a good partner, though agreements like this hurt consumer choice. When asked about the potential of availability on other carriers, Microsoft said that it was working to get both the devices on other networks, but had no news to share.
It's worth noting this deal is not exclusive, so it is very possible the Lumia 950 will be offered by more than just AT&T. Additionally, both the Lumia 950 and 950XL will be offered off contract through Microsoft's online and physical stores, which means T-Mobile users will be able to buy and bring either of those devices to their network. So far the only listing on the Microsoft Store is for the Lumia 950XL. The 950XL will run $649 off contract while the 950 will cost $549 when they become available in November. As of the writing of this article, AT&T has not provided any details regarding how much the Lumia 950 will cost on-contract. You can see our hands on of both of these new devices here.