A method includes receiving a media signal at an interface device in communication with and disposed between an Internet Protocol private branch exchange (IP-PBX) and a first endpoint. The media signal is associated with the first endpoint and is associated with a session established between the first endpoint and a second endpoint within a session over internet protocol network. The session is established at least in part by the IP-PBX based on a session control signal received at the interface device from the first endpoint and sent from the interface device to the IP-PBX. The method also includes modifying the media signal at the interface device based on a per-device service associated with at least one of the first endpoint or the second endpoint.