atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Telecom Service & Providers low volume

i have a customer complaining of low volume. his system is only about a year old. an sbx. phones are turned up. i did increase the volume with programming but they are getting rather loud side tone so i dont dare raise it more. my butset reads 36 milliamps when i go off hook. could this be why they have low volume. thanks dave

Hey Dave,

I'd like to see a reading around 25mA myself. 36 seems a bit down in the mud.

im going to advise them to call verizon to try to correct it. they arent always very responsive around here but doesnt hurt to try. thanks for the update. dave

If anything, 36 ma. would make it "hot." When checking for low volume, you need to do a "loss" test. Using a level meter (Sidekick or Dynatel or Triplett) dial into the telco's 1 KHz. test tone and read the level. Anything below -8db is usually too low for most telephone systems to handle. The old Belcore (which is now Telcordia) specification was 0 db + or - 3 db VNL. Today, however, that specification seems to have been lost to the operating companies. If you get a dribble at the end of the hose, they pronounce it "within spec." For a fairly good read, Click Here regarding loop current and line loss. The information is from Mike Sandman Enterprises and is fairly accurate.

The other situation may well be the telephone equipment may be damaged due to the high current. The old spec was between 25-35 ma. with 35 ma. being the absolute highest it could be. Even at 35 ma. I would install current limiting devices to bring the current down to near 25 ma.

Rcaman

Argh...I was thinking of decibels. -25 vs -36.

Wow, -25 db would be hard to hear, even with "new" ears. I have seen some old copper with -11db and the telco walked away and said "that's the best we can do." Even with amplifiers, -11db is a real stretch for most phone systems.

Around here, if one makes a fuss with Verizon, their standard reply is "have FiOS installed." That is their answer to everything. However I recently had a situation where FiOS actually made things worse. It seems they don't have adjustment control over line current and if the line current is low or high (i.e. less than 25 ma. or greater than 35 ma.) then you have to fix it. I have a feeling there is adjustment control and either the techs are being told they aren't able to change it or someone didn't read the specifications from the ONT manufacturer. Since line current is fundamental to proper telephone system operation, I can't imagine an ONT manufacturer would just leave that specific parameter to chance.

Rcaman

Believe it or not, you can believe it. We're the local phone company and have dozens of ONTs in the field with all sorts of different configurations and add-on modules and not a one of them has any way to control loop current. The soft-switches that control them have a difficult time with disconnect supervision, so life can get interesting at times.

I have not seen any other ONTs that Verizon uses except Motorola. I have not had the opportunity to tear one apart so I can't comment either way. Having done a lot of VHF radio work in my youth, and most every commercial radio was, at the time, Motorola, it baffles me to think Motorola would not make some sort of adjustment controls. The Commercial band radios had more adjustment controls than they needed. But, my friends all tell me that's "progress."

Rcaman

I just chalk it up to equipment and processes designed by IT types and not telephony types. IT types use protocols that basically look for the presence of a signal- levels don't really mean too much for the most part. High loop current? Low loop current? Sorry.

Disconnect signalling? What is that for?

The two types of transport can communicate with each other pretty well. They have the same 'vocabulary' but the accents and dialects still need to get along better.

This isn't your father's Motorola anymore.

Unless your father was Chinese...

-Hal