ESPN3 is not a channel that is available for traditional television viewing through AT&T's U-verse or any other cable service provider. Instead, ESPN3 is an online viewing option provided by ESPN offering some of the programming of the ESPN networks. ESPN3 can be found at WatchESPN.com.
The intent of ESPN3 is to allow access to programming far beyond what the ESPN network is able to air on its mainstream channels. For example, on a Saturday in the fall, ESPN is physically unable to air more than one game per channel for each time slot throughout the day. ESPN3 allows the company to provide access to other games that may have regional or niche appeal through its website in addition to the nationally televised options on ESPN, ESPN2 and ESPNU.