E1VI cable compatible issue with some PBX

Publication Date:  2012-07-27 Views:  76 Downloads:  0
Issue Description
when connecting the RJ 45 (120 OHM) of the E1VI module port to the E1 port of PBX , e1 port still down when make (show controller e1 ) command
Alarm Information
the LINK LED of the E1VI port is still off (turned-off), and the LED of the E1 port of PBX is turned-off.
Handling Process
first, i checked if the PBX is performing CRC check on frames or not , so i found that it make CRC check , and also the router make Framing CRC ,and no problem ,also check the clock source ,(is the clocking mode of the px is external or internal , it was external clock source and the E1VI clock source is internal , and no problem , so , i start checking the physical layer of the cable : in the E1VI port there is 4 wires(Tx Tip ,Tx Ring and Rx Tip,Rx Ring ) and the the RJ 45 cable which provided with the Module is Direct connection so i change the connection to cross cable (TxTip,TxRing of the E1VI port of the router connected to RxTip RxRing of E1 port of the PBX ), AND(the RxTip,RxRing of the E1VI port of the router connected to TxTip ,TxRing )and after that the LINK LED of the E1VI module of the router is turned-on and when make (show controller e1 ) the port was UP .
Root Cause
when connecting the E1VI port to PBX , first you check of the physical connection of the e1 port of the pbx , sometimes the pin assingment is the same with E1VI port in router so , it is needed to cross the wiring (use E1 cross cable )
in certain router test regarding the voip solution , we connect one quidway router with one FXS port connected to telephone set and one E1VI port connected to LG PBX E1 port , the LG PBX support only PRI signaling type , the clock source of the PBX was external , so the route should provide the clock to the PBX , sothe clock in the router should be Internal.