I have about 30 DRU-s connected to my 2400ICS via E1-s to supply analog and digital phones to different buildings in a campus environment. I use fiber multiplexer to run several E1-s to each buildings. This setup has been trouble free since the last millennium (literally!).
All of a sudden, a phone doesn't ring. It's an analog phone. Then the next day, another one in the same office stops ringing. You call it, and it doesn't ring - there is no ringing voltage on the line. If you pick it up, you can talk to the caller no problem. Both phones are on the same DRU. OK, maybe it's the DRU. I replace it, problem persists. OK, maybe the DRU interface card in the switch. I replace it - voila! It's working now. The phones ring again - but only for 2 minutes before the problem comes back again. OK, so it's not the DRU and not the interface card. Fibermux or fiber? Can't be - all other E1-s work fine on that line.
Unprogram all the phones from the DRU, and re-program only the 2 phones that have the problem. Test - both rings fine. Keep testing for half an hour, both working. OK, start re-programming all the other numbers on that DRU. After about the 8th line re-programmed, the 2 phones stop ringing again. Un-program the last line, phones ring again... Re-program the last line, phone don't ring...
What's next? Unprogram all the lines, take out the DRU interface card and put it in another slot (in another Module Group). Re-program all the lines and the phones are all ringing as they are supposed to. GREAT! Next day: the problem comes back
So what is it? One E1 channel on the Fiber mux? Doesn't seem like it, since the ringing problem came and left as I was programming up the DRU with phones, and when I unprogrammed the phones, the ringing problem vanished.
Memory corruption in the switch? Maybe. I just can't really shut it down to reset it, as there are 1000+ users expecting phone service 24x7x365.
What on earth is going on here??!?!?!
Anybody has some input on this?
All of a sudden, a phone doesn't ring. It's an analog phone. Then the next day, another one in the same office stops ringing. You call it, and it doesn't ring - there is no ringing voltage on the line. If you pick it up, you can talk to the caller no problem. Both phones are on the same DRU. OK, maybe it's the DRU. I replace it, problem persists. OK, maybe the DRU interface card in the switch. I replace it - voila! It's working now. The phones ring again - but only for 2 minutes before the problem comes back again. OK, so it's not the DRU and not the interface card. Fibermux or fiber? Can't be - all other E1-s work fine on that line.
Unprogram all the phones from the DRU, and re-program only the 2 phones that have the problem. Test - both rings fine. Keep testing for half an hour, both working. OK, start re-programming all the other numbers on that DRU. After about the 8th line re-programmed, the 2 phones stop ringing again. Un-program the last line, phones ring again... Re-program the last line, phone don't ring...
What's next? Unprogram all the lines, take out the DRU interface card and put it in another slot (in another Module Group). Re-program all the lines and the phones are all ringing as they are supposed to. GREAT! Next day: the problem comes back
So what is it? One E1 channel on the Fiber mux? Doesn't seem like it, since the ringing problem came and left as I was programming up the DRU with phones, and when I unprogrammed the phones, the ringing problem vanished.
Memory corruption in the switch? Maybe. I just can't really shut it down to reset it, as there are 1000+ users expecting phone service 24x7x365.
What on earth is going on here??!?!?!
Anybody has some input on this?