The GSX range has a basic controller called a GSX 408. This permits the interfacing of up to 4 incoming lines with up to 8 extensions. The controller can be upgraded to a GSX 816 that permits up to 8 incoming lines from the PSTN and up to 16 extensions.
Starting from a different chassis gives a larger system controller. The GSX1832, which handles up to 18 input lines and up to 32 extensions. It is possible to upgrade this to a GSX3672 – which offers up to 36 input lines and 72 extensions.
Making the upgrades is via a series of plug-in cards. These include:
- CO cards: add up to 6 phone lines into the controller.
- KIB cards: add up to 8 extensions per card
- SIB cards: designed to let you add the low cost analogue handsets.
Note that the GSX controllers did not have an ISDN card, and so is only for analogue connections out to the PSTN.
