We still experienced the same issue. Cannot call to MTSG via ext.
We have check with our PABX vendor but according to them our PABX also doing good.
Since have affected MTTH, I have request them to check further.
In this now, I can ping or tracerout to MTMY Network and MTSG Network as normally.
But I still can’t calling to MTSG or MTMY and panel on telephone shown system busy