need help with diagnostic

[mccarron]

I'm a network guy. Not a telephone guy. My boss asked me to look at a problem a non-profit that's next door to us and see if I could do anything. I guess its are good deed for this month.

They have NT7B56 telephone switch with two lines to the outside world. Eight telephones internal. Meridian phones 5310.

There problem is that one of there line gets no dial tone. It sounds like someone hung up on one end and it didn't hang up on the other. I went to the demarc and was able to call out and receive calls in. I toned out the line between the demarc and the switch and that seemed good. I disconnected all the phones and then reconnected them one at a time thinking that one of the phones may have been bad, but I still can't get any dial tone.

What else can I do to diagnose the problem. I tried to get into the maintenance routine, but there was no down arrow that the book says there should be.

Any help would be appreciated. What do you think the problem is. I can't find anything about the switch on the Nortel website so I assume that thing is so old they have given up on it

 

[curlycord]

Try swapping line 1 with line 2 at demarc.

You have a Norstar CICS KSU phone system.

 

[ChicagoTech5555]

for info on that system type in the part number on google and you should be able to get some info.

 

[DaveUK]

You might also try reversing the non functioning line pair A and B leg, some Nortel systems are polarity sensitive on the external loop lines.