A system for temporary user association based on call state in a communication between a plurality of participant communication devices (631, 632, 633), comprising: a call state engine configured to maintain an internal state model of the current operation of a first participant communication device based on the call state of the first participant communication device, wherein the first participant communication device is configured to operate the call state engine such that the call state engine is configured to recognize when a call or another communication takes place; and an association service configured to generate a temporary association between one or more participant communication devices of the plurality of participant communication devices (631, 632, 633) based on the call state of the first participant communication device; wherein the call state engine is configured to notify the association service that the call or the other communication is in progress, wherein a plurality of external communication services, external to the call between the one or more participant communication devices, are available to the first participant communication device and to a second participant communication device, wherein the plurality of external communication services of the first participant communication device is associated to the temporary association based on the capability of the first participant communication device, wherein the plurality of external communication services of the second participant communication device is associated to the temporary association based on the capability of the second communication device, and wherein communications are enabled from an external communication service of the first participant communication device to a compatible external communication service of the second participant communication device using the temporary association, such that specific access criteria for the external communication service of the first participant communication device and specific access criteria for the external communication service of the second participant communication device are not required to enable the communications via the external communication services. a call state engine configured to maintain an internal state model of the current operation of a first participant communication device based on the call state of the first participant communication device, wherein the first participant communication device is configured to operate the call state engine such that the call state engine is configured to recognize when a call or another communication takes place; and an association service configured to generate a temporary association between one or more participant communication devices of the plurality of participant communication devices (631, 632, 633) based on the call state of the first participant communication device; wherein the call state engine is configured to notify the association service that the call or the other communication is in progress, wherein a plurality of external communication services, external to the call between the one or more participant communication devices, are available to the first participant communication device and to a second participant communication device, wherein the plurality of external communication services of the first participant communication device is associated to the temporary association based on the capability of the first participant communication device, wherein the plurality of external communication services of the second participant communication device is associated to the temporary association based on the capability of the second communication device, and wherein communications are enabled from an external communication service of the first participant communication device to a compatible external communication service of the second participant communication device using the temporary association, such that specific access criteria for the external communication service of the first participant communication device and specific access criteria for the external communication service of the second participant communication device are not required to enable the communications via the external communication services.