The PBX is using two PRI (ISDN card), for incoming source from service provider and the second PRI card for connection to media gateway. The PRI card has to be enable QSIG signalling to communicate with the media gateway (as media gateway will require min. QSIG signalling). With this, the normal fax machine will still able to be connected to the PBX system.
During the implementation, the two connections (service provider and to media gateway) are require to use coaxial cable (with BNC connector as standard). Due to media gateway are having RJ45 connection only, we uses balun which conver the coaxial (BNC 75ohm) to RJ45 connection (RJ45 120ohm).
PBX is configured as slave as accepting the source from service provider and media gateway would need to be configured as master.