A recent storm in South East Queensland resulted a service call to Stanthorpe for our bank customer with the complaint that the ISDN2 was down and could we investigate. Telstra had already been to site and proved the ISDN was OK so was it a circuit fault or equipment fault? Loaded up with a spare phone system (Avaya IP500v2 with BRI module) and a handset, my tech made the 3 hour drive to site to see what was going on. On arrival the Sync light was off indicating it wasn’t talking to the Cisco Voice Interface Card.
My tech plugged in the Avaya but the circuit still didn’t come up. It took several power cycles of the NT-1 for it to sync up to the Avaya so calls could be made. In talking to the bank’s Network Operations Centre when the ISDN was plugged into the Cisco, the card was showing up but there was no data flow. They agreed there was a dead card (both ports on a dual port card). It is odd that the NT1 appears OK but the voltage spike passed through it to kill the card. We had a similar situation at the Canungra branch and their ISDN going down after a storm.
Like all fault finding, a methodical approach is essential. We know what should occur but why doesn’t it. Go back to the beginning and work it through. Power cycling can definitely help. In this case the ISDN NT-1 had been trying to sync with the dead card for so long it had given up and gone to sleep.
We always apply a methodical approach to fault finding and using the available tools can usually solve obscure faults that others can’t. Please contact us for assistance.