This information could theoretically come from the account information, but is not done this way in practice. Many consumers use different billing addresses from the primary location where they use their VoIP. There are now two common methods for populating ALI info.
Over the top VoIP providers, such as Vonage, have a big notice about E-911 issues with their service, and make each customer populate their own ALI information in their online account. This is somewhat risky, since these VoIP service tend to be nomadic-I can use my Vonage ATA to connect to any broadband connection, and if I change my location, it is up to me to update my ALI status. (There are horror stories of people setting up at a hotel, having a heart attack, calling 911, and having the ambulance show up at their house).
Providers of integrated VoIP, such as Comcast, have developed ways to use the IP address associated with the VoIP call to lookup the physical address of the caller. This works because Comcast is also providing the underlying broadband connection, which is tied to a particular physical location.
The FCC discussed these complications in a 2005 Order which required providers like Vonage to take extra steps to notify customers about the 911 risks, and to collect accurate ALI information.