- configures 
X.21/V.35 ports. Note that this is only available if an X.21/V.35 card is installed and detected at Power-up: otherwise, the option will be greyed out.
X.21/V.35 configuration dialog:
Item to select if X.21/V.35 port 1 or 2 should be configured.
- sets the X.21/V.35 port Mode to either DTE or DCE.
In DTE (Data Terminal Equipment) mode, 
receives its clocking information from the network - or a dedicated line.
In DCE (Data Circuit Equipment) mode, itself supplies the clocking information.
In most cases, the DTE mode will be used.
- sets the clocking format of the X.21/V.35 port.
In DTE mode, T4 clocking is usually used.
In DCE mode, T2T4 clocking is most commonly used.
The meaning of the different clocks is described in the Interface Manual (link: www.mayah.com/content/download/pdfs/manuals/centauri-interface_eng.pdf).
- selects the fixed line’s connection protocol to either X.21 or V.35 format.
- sets the audio delay applied to the X.21/V.35 interface. The maximum value is 5,000 ms.
Increasing this value can make X.21/V.35 connections more stable, by providing a larger (longer) buffer. For instance the audio delay buffer can compensate jitter problems.