Digital exchange with grouped subscribers accessing switch block - has subscriber line units which contain coded(s) and primary switch with full availability to main exchange switch-blocks

摘要

The multistage switched digital telephone exchange is arranged so that each subscriber line is connected into a CODEC and each group of subs is connected into a first switching stage with full availability. The exchange design enables it to be readily extended as demand requires. Each subs line unit(AO) contains a CODEC, for the conversion from analogue to digital, with its output connected into an intermediate switching stage(ZSE) which has at least two parallel accesses to the second switching stages(BFK1,BFK2) of which there are at least two in the exchange. Each subscriber line unit(AO) is part of a group(Gr1,Gr2,Grn) with full availability trunks(AKF1.1,AKF2.1,AKF2.2, AKF1.n,AKF2.n) to the second switching stage (BFK1,BFK2). The CODEC samples at 8kHz and each subscriber line unit(AO) contains storage and multiplexing so that switching through the exchange can be at a higher bit rate than the sampling frequency and each incoming signal can be stored for accessing the allocated time slot.