sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services Telecom Service & Providers AT&T 955 phones and Fios

Ran out for a service call where new Fios had been installed in an office with [4] AT&T 955 4 line phones . The line in use indicator lights had stopped working and phones would not pick up next idle line when handset was picked up. If I picked any of 4 lines could get line light but other phones did not lite line indicator lights. All inbound and outbound calls work fine. All phones worked fine before 4/30/09 Fios install. This is on new release Motorola ont 1500 GT 8 line unit. This is first time I have ever come across phone issue other than fax with Fios.

What is the on-hook DC voltage across Tip and Ring of the imitation phone lines? Bet it's somewhere around 28 volts, rather than 48 volts. Some phones have a setting for low line voltage, but I don't recall the 955 phone having one. John C.

All things being equal, the 955s shouldn't be able to tell the difference between FiOS and standard telephone service.

As Lightninghorse mentioned, low voltage could also play a roll in all of this.

Just for giggles, I checked the voltage out of the Tellabs media converter Verzion installed at our house. I set my Simpson voltmeter for -50Vdc and the needle shot right the edge of the scale.

One thing you can try doing would be to disconnect all but 2 sets and see if the LEDs start to function normally. If so, start adding more sets until either everything is reconnected or the problem returns.

This might also be a good time to suggest to the customer that they upgrade to a real business telephone system.

John C is correct voltage a little low and the wire length total for 955 units are already over 600' with existing cat5e wire which puts total length even higher. They have new system proposal in hand. I posted because this was a first time event and we might see it in future.

In practice, we try to steer all but the smallest of companies away from NoKSUs.

They might be good in a home office setting or even as a fancy residential setup, but beyond that, a true business telephone system is the way to go.

Dexman
Systems are all that we sell and this was a referral from the Verizon Fios installer who still had a few of my cards. I owe him lunch and perhaps more if system is purchased. I agree about these stand alone phones, have installed jacks for people who use them and they don't seem to last.

Agreed. :thumb:

It is pretty much a given that stand-alone 2,3 or 4-line phones require very precise CO line voltage tolerances. It is variations in the voltages (the ones that are expected) that let the phones know what should be displayed.

If they are expecting 43-56 volts and they consider 6-12 volts to be an off-hook condition, then you can imagine what would happen when the line voltage is reduced by half?

Unfortunately, this happens very frequently with pair gain equipment, channel banks or integrated access devices. These things typically throw out voltages in the 28-32 volt range. This works for a butt set, but this is way outside of industry specs that these phone models are designed around.

Telco technicians usually verify dial tone and that is it. That is the problem. They don't know what else to test, if they even have the means to do so.

Hi- Do they make some kind of adapter that I can put on the line that will bring the voltage back up?

Viking Electronics makes a booster LLA-1 Information that will solve this problem, but it isn't cheap. They also make a four-line version.

I don't feel as if the customer should have to bear this expense, but in some cases it is the only solution. After purchasing four of these units, it may be less expensive to buy a traditional telephone system.