The answer is not straight forward. It all depends on what you're talking about when you say PBX and its capabilities.
If you connect a proprietary terminal behind a digital PBX and the PBX can somehow ensure that the encoded content, if decoded somewhere in the network, will not exceed maximum level provisions, you don't have to do anything with the terminal. However, because of all this, terminals MUST be certified/registered with and as part of a PBX. The FCC has a special code for that. In the old days of step-by-step PBXs, which merely performed a cut-through function, the terminals had to meet all the normal requirements, because, after cut-through, they were connected to the network. Merry Christmas, Vic Boersma
