Ring Voltage Measurement

Posts: 646 · Posted: Tue Jun 21, 2005 7:22 pm Post subject: Ring Voltage Measurement

Has anyone tried putting a volt meter on their phone line during an incoming ring? Last time I called Vonage, they supposedly set my RT31P2 ringer to 90V, but I'm now only measuring about 56V AC.

I'm bringing this up because I have a Motorola cordless phone that sometimes doesn't ring, although it lights up and shows the caller ID info. Other phones in the house are ringing fine.

So what sort of voltage readings are you guys getting? (you can click2call yourself to trigger a ring).

Posts: 2 · Posted: Wed Jun 22, 2005 10:14 pm Post subject:

Of course my first post is techie related. I checked my phone when I got home and my standing voltage was 50.5 volts. Ring voltage was -55.0 volts. I also noticed that the REN is really low on this thing at 3.5. Mind you this is on my old Motorola VT1005v.

If Vonage is going to compete with the LEC/CLEC they are going to have to support house wiring and multiple phones. I can see as being a problem in the future for them. I am amazed to see how many have hooked up other devices to the line and they work like alarms, faxes, Tivo, etc..

Let me know if you have any more questions because I love testing these things.

Posts: 646 · Posted: Wed Jun 22, 2005 10:34 pm Post subject:

Were you measuring AC or DC? If I measure AC, I get 0V at idle, but it jumps to 56V during a ring. If I measure DC, I get about 45V at idle. I haven't tried measuring DC during a ring.

Also, when I measured right at the box instead of running it through the house, I got over 90V AC at idle... but I assume I was just picking up some random noise because no phones were loading it down.

Edit: the 90V AC at idle disappears if I swap the wires. Go figure.

Posts: 2 · Posted: Thu Jun 23, 2005 11:45 pm Post subject:

The readings I got were in DC. If I measure the ring voltage in AC I get 102v.

Posts: 646 · Posted: Fri Jun 24, 2005 12:56 am Post subject:

I just called and had them switch me to 20Hz, 90V, Trapezoidal. Those are the settings that made the most sense to me because:

- 20Hz is the standard US frequency
- 90V is the highest, and has the most chance of being detected.
- A trapezoidal wave can be generated much more efficiently by a DC device, and more easily detected by a digital circuit like a cordless phone.

With those settings, my Motorola phones now seem to be ringing with much more predictably that they were before at 25Hz, 90V, Sinusoidal.

Also, my measured AC voltage is now at 63 Volts (up from 56V).

Another thing I found interesting... when my RT31P2 was cranking out sinusoidal rings, I could actually hear the box buzzing slightly. On trapezoidal, it's silent. That supports my hypothesis that the RT31P2 doesn't have to work as hard to crank out the trapezoidal wave.

Posts: 1715 · Posted: Tue Jul 12, 2005 12:34 pm Post subject:

What sort of meters are you guys using? I'm willing to bet that you're not using a Fluke or other high-end meter. You're measuring sine waves, so to do this accurately, you'll need a meter which reads true RMS. The cheap meters don't do this. I'd assume the Linksys/Motorola TAs are powered by a standard wall-wart, probably 12vDC. They're most likely using an inverter circuit to generate the ring voltage. Considering how cheap these boxes are, I doubt they spent major money on this part of the device, so it's probably putting out a modified square wave rather than pure sine wave. Most of the cheaper (<$200) will not display modified square wave output voltage correctly, usually underreporting it.

Posts: 16 · Vonage Forum Associate Joined: Jun 25, 2005 Posts: 16

I have a wrtp54g and noticed that the ring pattern with it is different than when I had my old POTS. What would I need to request it be set to to have it have the same ring pattern? It seems to come in and die out really quickly.

Posts: 646 · Posted: Tue Jul 12, 2005 1:32 pm Post subject:

ziddey:
I'm not sure how the WRTP54G differs from the RT31P2, but you might as well try my suggested settings and see if it fixes anything. Maybe your phone is ringing quickly because the signal is abnormal and it doesn't get detected right away.

VonageTPA:
I'm just using a cheap meter, but it does still seem to indicate that the square wave pattern is relatively stronger. The most important thing, however, is that my phone rings properly with the new settings (20Hz, 90V, trapezoidal), but not with the defaults.

If I could mess with the settings without calling CS, I'd be able to determine for sure whether the root of the problem is the shape, or the frequency. (Voltage by itself seemed to have no effect)

Posts: 16 · Vonage Forum Associate Joined: Jun 25, 2005 Posts: 16

paul248 wrote:

ziddey:
I'm not sure how the WRTP54G differs from the RT31P2, but you might as well try my suggested settings and see if it fixes anything. Maybe your phone is ringing quickly because the signal is abnormal and it doesn't get detected right away.

VonageTPA:
I'm just using a cheap meter, but it does still seem to indicate that the square wave pattern is relatively stronger. The most important thing, however, is that my phone rings properly with the new settings (20Hz, 90V, trapezoidal), but not with the defaults.

If I could mess with the settings without calling CS, I'd be able to determine for sure whether the root of the problem is the shape, or the frequency. (Voltage by itself seemed to have no effect)

wait, so you're saying that your Vonage rings exactly the same as any other pots phone should ring?

Posts: 20 · Vonage Forum Associate Joined: Jun 29, 2005 Posts: 20

So here's the dumb question of the day. I can't seem to find an answer by searching but you people sound like you should know the answer.

If Vonage can program my Linksys RT31P2 to put out more voltage, does that just apply to the ringer or can they increase the actual line voltage it puts out (like during a phone call)?

Thanks in advance.