учрежденческая АТС с исходящей и входящей связью (с городом)
(PABX) A telephone exchange operated within an organisation, used for switching calls between internal lines and between internal and PSTN lines. In contrast to a PMBX, a PABX can route calls without manual intervention, based entirely on the number dialed. Not all PABXs can route external calls to internal numbers automatically however.