Most "t38.rar" files found on community forums like the Microsoft Flight Simulator Forums contain 3D models, cockpits, and flight dynamics for the Northrop T-38 Talon aircraft.

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In technical contexts, it may contain packet captures (PCAPs) or firmware related to the T.38 protocol , which is the industry standard for sending faxes over IP networks. 2. Required Software

T. 38 Real-time facsimile (T. 38) The T. 38 protocol is used for Fax-over-IP; it is a member of the VOIPProtocolFamily. Wireshark Wiki