Described are systems, methods, and apparatus that enable constraint based communications between two or more devices. For example, a first user of a first device may submit a communication request to establish a communication session with a second user and provide a constraint for that communication session, such as a time-limit (e.g., limit the communication session to five minutes). In such an example, if the second user accepts the communication request with the constraint, a communication session is established and the system monitors the communication session to determine when a condition corresponding to the constraint has been satisfied. When the condition is satisfied, the communication session is terminated by the system.