A system and method are directed towards detecting that a client is participating in an online service such as an online multiplayer game. A client probe module monitors an operating system process list to detect an executable file name, indicating that a client program is executing. The client probe evaluates client program communication to determine whether the communication is consistently directed to the same online service and meets a predefined communication rate threshold. The executable file name and communication rate threshold are provided before the client probe begins monitoring the process list. Meeting the threshold may cause the client program to instruct a client messaging module to send a message to contacts associated with the client through an independent portal service. The contacts may not be registere members of the online service, but the message may include information that enables th contacts to communicate with the same online service.
