Multi line phone "Line in Use" trouble

Posts: 1 · New Forum Member Joined: Oct 09, 2005 Posts: 1

Hi, I have a small office with 16 phone drops only (6) in use at this time with 4 Vonage lines (3 voice 1 fax). The drops are comprised of cat6 ran in a Homerun fashion. All coming back to a main distribution panel where the 3 Vonage voice lines are terminated/distributed from. The 6 drops in use have AT&T 974 4-Line phones installed. This is how the lines are brought in from Vonage.

RTP300 - Voice Line 2 and 3
PAP2 - Voice Line 1 and Fax Line

I have had a number of problems. These phones have a number of features like "Line in USE" "Line Privacy" (where no other extension can access the line you are currently on) and Intercom. The first problem I had was that I would get phantom intercom ringings from one extension to the next. Sometimes even from extensions that are not present on the system. I installed an ATT Z800A filter on the Vonage line coming into the line one position of the distribution panel. This seemed to clear up that problem.

I am still having trouble with the LIne in Use (LIU) option. Each of the 4 lines on the ATT phone has an LED that will light up when any other phone "off-hooks" that particular line. This works in the fashion that typically when you take the phone off the hook it drops the line voltage from 48v or greater down to a range close to 7 -9volts. When the phone detects that for the line it lights the LED. This works sporadically when I have all of the lines connected. I originally had all 4 lines connected with line 4 being the fax. In this setup Line 2 and 3 worked with no problem but Line one would blink the led for a moment and then go off and on. Once I pulled the line 4 which was the fax line line one's LIU option worked fine. So I thought it was the fax. But now Line 2 and 3 are doing the samething remember they share a Voip adapter. If I pull line 2 from the system then the LIU works fine for LIne 3 and Vise Versa. I was on the phone with Vonage Tech and had them modify the voltage and impedance on both adapters with no realized benefit. As it stands if I only leave in one line from each adapter say line 1 and 3 then it works fine but this is not an option as I need all 3 voice lines. Any suggestions. Without the LIU option we are picking up on each other's calls left and right.

Thanks for any help in this matter.

PS I have checked the line voltage on line 1-4 as follows
On-Hook 48.5 - 49v
Off-Hook 5.6 - 5.9v