What Are User Identifiers?
User identifiers include device IDs and user IDs.
A device ID is the ID of a device used by users. The devices can be a plain old telephone service (POTS) phone or a user agent device, such as IP phones and software.
A user ID is a unique number assigned to a user. A user ID is the owner of a device ID, and indicates a user's identity. A user ID and a Session Initiation Protocol (SIP) server domain constitute a URL. A device ID can belong to multiple user IDs.
Each user has a fixed user identifier, which is bound to a unique device ID. Usually, a user identifier is the global number or long code for the user. Users can dial long codes to call each other, which is the common dial-up mode. Internal numbers or private numbers are provided to users inside the same group, such as an enterprise, company, group organization, school, or hotel. Users in the same group can dial each other's short numbers or private numbers.