We have a SBX that when the I press a line buttons 1-3 all I get is a clicking sound followed by a CO release busy. Line 4 is fine. I get the same thing when dialing 9 if I busy out line 4. If I swap line 4 with lines 1-3 they are fine so it is definately a line issue. Tech support tells me it is because the line voltage is too high. I am reading 55 volts on all the lines including line 4. I know the lines should be 48 volts but 55 does not seem that high. I know there are line amplifiers out there but do they make anything that will lower the voltage on a line. I really can't see Verizon helping me with this since the lines are fine when testing with a butt set.

One other question has anyone had any issues with caller ID on a wave 2500 with analog lines?

have you looked at loop current ?

have you checked the lines a the demark with a buttset ?

I am getting 35 mA off hook. Unfortionately I can't test the current on hook. The lines are all testing fine at the demarc except for the voltage being high. I can go off hook on all the lines and get dial tone.

May want a different system SBX is very picky with line conditions.

Apparently. I have an old partner acs in between the SBX and the dmarc. Thats keeping the customer happy. It looks like crap though. I'm still waiting to hear back from engineering on this.

It's something that probably won't change, it's just the way they are. One of the biggest problems with the SBX's, other than that they're pretty solid. We had a few where differing line conditions caused problems also.

The line current is probably too high. You need to build it out with resistors, or get a Sandman loop current attenuator. 25 mils should be enough.

The resistor build out can be as simple as adding a 100 ohm resistor to both tip & ring. This cheap fix costs next to nothing and may do the trick.

Call me crazy, and I probably am, but shouldn't a system's CO line ports be more tolerant of variables as long as they are in compliance with FCC mandates? Just asking.

Ed, I recall older posts about the effects of high current and voltage. I think members described their systems as behaving in different ways. I used to see echo on Vodavi analog systems and didn't Hal say the ACS sometimes burned out the CO Circuit packs on high line voltage?

Ed, you're crazy. (You did ask for it.)

However, you are correct that manufacturers SHOULD make their stuff able to tolerate the full range of allowable voltages and currents. But many, many problems can be traced to high (or low) line current.

The problem is Ed there is no upper limit on loop current, just a minimum. I too have seen weird problems due to high loop current.

Actually, the FCC upper and lower limits are 23 ma and 120 ma.

Arthur, if you have any offical documentation that shows that I'd like to see it.

While I've seen the same limits you're stating I've never seen the ANSI, Telcordia, EIA, Bell System standards, or any other standard that actually stated it.

If you search on "loop current" on the forum this question has been asked many times.

Which should probably be addressed in a new topic or one of the loop current topics.

Thanks for all the info. The only standard I found was TIA 968-A which is referred to in the FCC part 68. If I'm reading it right the loop current should be between 23 - 120 ma. the dc voltage should not be more than 56.5. Now I know there are alot of standards out there but which one does Vertical/LG use to design these systems. I have asked them but still have not received an answer. I had one tech tell me something about ITU but that didn't come from an engineer. Unfortionately I could not find that standard free online. I would think that if it is a standard they are going to use then it should be available free or the manufacturer should be able to supply us with a copy. I will try the resisters when I get a chance. I did read that it should work.

JBW, where in that document did you find the values. I searched loop current in the document but didn't find those values. Could you give me the paragraph or page? Thanks.