Establishing a telephone call includes enabling display of a visual indicator of a call destination entity and detecting selection by a user of the visual indicator. The availability of the user to receive a first telephone call is determined. Voice communications between the call destination entity and the user are established in response to detection of the selection by the user of the visual indicator and conditioned on the user being determined to be available to receive the first telephone call. Establishing voice communications includes enabling placement of the first telephone call to the user to establish a first PSTN link with the user and enabling a voice communications link to be setup with the call destination entity.