In the past, a T4 clock output based on TU G.703 § 13 with wave resistance of 120 ohms was frequently required for clocking transmission equipment. An adapter for a shelf used to exist for this and was followed by the AECB or AICB. The demand for this clock is very rare these days. This is why it no longer exists in the OpenScape 4000 with cPCI controller.

An SASE/SSU is often required for the networking clock generator function. The SASE then provides all T4 clocks for transmission equipment and for the OpenScape 4000 front reference. This output is therefore no longer required.