sundance-communications.com/forum Forums TDM Business Telephone Systems Avaya - Lucent Telephones & Systems Definity-OPX

We have 2 OPX's off our Definity G3,V6, to a remote site about 5 miles away with a key system. The OPX lines both have a noticeable hum on them and have had since installation. The remote folks have lived with it for 2 years and now they wont anymore.
The telco says it is a phone system problem, the dialtone from our switch sounds good until I punch it down to the OPX circuit. Has anyone had such a problem? Any ideas?

I have seen this many times with opx circuits . You need to pull the jumpers at the remote site demark and see if the hum goes away . If it does the trouble is at the remote site wiring or ksu . If it does not then it's either telco or the wiring at the local site .

I pulled the jumper, the hum stayed on the line. This to me sounds like a telco issue but just to complicate things, I put dialtone from a telco 1B line in place of the PBX OPX station and it had no hum at the far end and sounded good. This sounds like a PBX problem.

Are the pbx stations 24 volt or 48 volt .The telco ckt build out may not be correctly optioned if the 1mb works ok .

The pbx station is 48 volts. I think the telco line is 48vdc also.

We used to order the OPX circuits as OL13C's and had that type of trouble with them. We started ordering OL13B's and they worked a lot better. The letter designation has to do with the resistance (ohms) that are expected. You should probably check with the telephone company and find out what type of circuit you have. If it needs to be changed, it's just jumpers or option switches in their equipment, but I am sure that there will be a charge for it.

Check and see if your opx's are 48 volts 9oo ohms . If they are your telco needs to reoption the equipment as EV stated .