A system and method are provided for managing diagnostic and performance information for communications system terminal endpoints (TEs) communicating over an Internet Protocol (IP) network. The TEs communicate by transmissions that are voice, modem, facsimile, video, data transmissions, or the like. A Diagnostic Supervisor (DS) transmits Diagnostic Configuration Messages (DCMs) to the TEs. The TEs generate Diagnostic Messages (DMs) based on diagnostic information, including error statistics, voice statistics, facsimile statistics, video statistics, data statistics, or the like, concerning IP network transmissions in which the TEs participate. The DCMs instructs the TEs how to format and when to transmit DMs. The DMs are transmitted by the TEs to the DS. In a system with more than one DS, the TEs can transmit DMS to the plural DSs, other TEs or any network devices.