Phone line voltage

Old 01-07-03, 05:53 AM
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Phone line voltage

I am troubleshooting my rural phone system for slow connect speeds before I call my utility.

I have first checked my outside distribution box and it appears dry and the connections look secure.
I made up a test set from an old phone and it sounds like I get a really faint hum inside but not outside. hard to tell though because there is more background noise outside.

The wiring at the jacks in my office look suspect. I will fix that up next.

My questions:

Does the phone line voltage have any bearing on connect speed?
What should the voltage be at rest and at ring and is it a/c or dc?
You can get boosters for a lot of things, is there such a thing as a phone line booster that can improve line performance. (Promise it will be our secret.)
Is having a hum be louder inside a valid occurance, or should the line noise be the same inside as outside?
Old 01-07-03, 07:42 PM
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First, line voltage on a typical telephone line is...
-48 volts DC (on hook)
-5.1 Volts DC (talking)
96 volts AC (ringing)

If there is a much lower reading then I would be concerned. I would say no more than 4 volts for the on hook voltage and no lower than 80 on the ringing. Test it with your home wiring connected or disconnected, check to see if it is different. I would also listen with the test phone you made very close to your ear then when you have dial tone tap any digit, it should be quiet with no hum. Again, do this with your in house wiring connected then disconnected to see if the noise gets louder or doesn't change. If the noise doesn't change with your wiring connected then it is an outside issue, if it does it's your stuff.

As far as "boosters" go. No, there really isn't anything available that would do such a thing. If you were to boost the voltage you would smoke your phones and probably amplify the noise. Depending on the distance you are from the central office there may be things called "Load Coils" These basically can be considered boosters so to speak. They basically amplify the signal as it will weaken over a great distance. It's kinda like the two soup cans and the string. You will hear each other talking into the can to a point but eventually you won't if the string gets too long. I don't know how to amplify soup cans but the telephone company uses these load coils out in the field. Again, each time it is amplified it will cause more noise. Just like cranking a stereo up, eventually if it is cranked too high it will sound terrible. Not to mention you will have to leave the room with your with your eyes crossed and your ears bleeding. Anyway, a poor quality line will cause slower internet connections but distance also plays a factor. Actually there are way too many reasons to list that could cause slow connection speeds. I would certainly check the line first. If you find humming on the line tell the phone company that, not that your connection speeds are slow. You will get more attention from the customer service people and probably the tech by telling them that its a hum. Just about everywhere we go we hear about dial up connection speeds being slow and it goes in one ear and out the other.
Old 01-07-03, 08:07 PM
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Good info.

Thanks Phonetech,

I get pretty good service out of our phone techs here as I occasionally coffee with them and have done a lot of a/c work in their building.

I just want to make sure my end is covered.

The lines here are generally not that great. We are less than 5 miles from the office, but they are unable to hook up the high speed internet here because of the crappy lines.
We are fed by an underground cable where large trees have been allowed to grow overtop of the line.
Not much fun for the guys.

I'm cleaning up a messy hook-up in my office tomorrow and will run a 3 pair line to my computer to eliminate a cheap extension.

I'll let you know how I make out.

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