An intermediate device receives a content data message addressed to a receiving device for a communication session between a source device and the receiving device. The intermediate device substitutes adapted content data for content data of the content data message and then sends the adapted content data to the receiving device such that it appears to the receiving device that the adapted content data originated from the source device. The communication from the source device to the receiving device is intercepted by the intermediate device in a manner that is transparent to the source device and receiving device.