I understand the importance in a POTS application as to how many phones you can connect, but, how advanced are you taking this and isn't there better alternatives?
Possibly a more serious answer than the one I offererd before. I found this article on how to measure REN using a standard 2500 set as a known value. Scroll down a bit on the page and you will see the details under "Measuring the REN of all the phones on the line". The article also talks about some of the problems with VOIP devices delivering out of standard ring voltages. http://www.sandman.com/ringvoltbul.htmljm9496 wrote:How do I measure REN for all phones on a line? Do I call the phone line and measure voltage and current when it rings to find the impedance? I suppose that would give me |Z|.
(in the US, 6930Ω resistor in series with an 8 µF is 1 REN)
I holpe this helps you determine what you were looking for.
VoIP hardware: 2 Telo w/3 handsets & Linx / ooma core
Total Lines: 8 / Numbers: 11 / Handsets: 20
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Friends don't remember what Landline Integration was or why we did it.
I measured 57 V AC, 30mA AC, and 20Hz when the line is ringing.
(57 volts) / ((6930 ohm) + (i / (2 * pi * (20 hz) * (8e-6 F)))) = 0.008059066 - 0.00115678228 i amperes)
|0.008059066 - 0.00115678228 i amperes| = 8.14mA
30mA/8.14mA = 3.7 REN
I know this implies REN is untiless. It is not. REN is a haphazard unit of impedance.