my customer has at&t 945 sets and just went from copper to fios. now most of the time when a user is on a line the other phones show the line busy with one blink every 5 seconds so it take a few seconds to know if its busy and most of the time there is no privacy. if they pick up a line in use they can hear the conversation. they say this started when they went to fios. can anyone recomend a phone that will work right or do they need a system. thanks, dave

I've never tried to use 945s with FiOS. Outside of:

1) Checking each phone's programming
2) Removing any/all DSL filters
3) Recheck all of the cabling
4) Test the electrical current out of the ONT

I can't think of anything else.

Now keep in mind that the 945s are old. Current at&t/VTECH NoKSU models are not compatible. Rather than fight with these phones, sell the customer a nice small true commercial telephone system. My Avaya Partner ACS works very well with FiOS.

Keep in mind that FiOS dial tone is not real, as in not to the same specs as traditional copper. In most instances, it is due to the lower line voltage that the FiOS ONT provides. Real lines are supposed to deliver somewhere in the neighborhood of 48 volts, where fake dial tone gadgets often deliver voltages that are much lower.

KSU-less phone 'systems' rely upon precise variances in voltage due to line condition in order to operate. For example, when going off-hook on a traditional line, the 48 volts drops down to somewhere below 10 volts. These phones are designed to monitor these changes in voltage to signal what is happening to the other phones on the line. With fake dial tone, these voltage relationships are pretty much tossed out the window.

Granted, these phones are old, but they're doing exactly what they are supposed to do. They're just being given bad information to work with when the line voltages are out of spec. Unfortunately, Verizon, Vonage, MagicJack, or most CLECs aren't going to do anything about it. In their minds, 'dial tone is dial tone'.

My Verizon ONT puts out 48vDC.

Does it drop to below 10vdc in an off hook condition? That's what gives the off hook indication on the phones. Not sure what would cause the slow flashing, all you can do is check your voltages to what it's putting out. Viking does make a unit to provide the correct off and on hook voltages.

I'll check it over the weekend to see what the old Simpson meter tells me.

i think i am going to recomend a phone system. thanks for all the help understanding what is going on. dave

I checked the offhook voltage. Looks to be about 8v.

Than yours should give the proper indications Paul.

Which would explain why my Avaya Partner ACS has functioned properly over the years.

Here @ Church, we have Verizon POTS lines (no alternatives available).

Onhook voltage = 49
Offhook voltage = 9.5

(According to my Fluke 189 DMM).

The current is a critical factor in how telephones and systems respond to voltage fluctuations. If the current is less than 25 ma. most system work erratically. Over 35 ma. and things burn up. If you have a combination of low line voltage and low current, nothing will work properly.

In our office, we have FiOS. My on hook voltage is -48VDC. My off hook voltage is -8VDC. My current is 28 ma. All my equipment is happy.

Rcaman