Dynamic telephone call routing. A voice service initiates a voice call session on a data communication network in response to an incoming telephone call directed to a user and generates a notification of the telephone call. An alerts service receiving and responsive to the notification executes a set of routing rules to select a computing device associated with the user. The alerts service also generates an alert directed to the computing device. If the computing device is online, a messaging service sends the alert to the computing device and receives a user request from the computing device in response thereto. The messaging service communicates the user request to the voice service for completing the voice call session to the computing device if specified by the user request. If the computing device is not online, the telephone call is routed to a telephone device.