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Length of wire allowed to be connected to OBI200 phone port

Started by gerald.stutts, June 28, 2018, 06:50:13 PM

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gerald.stutts

I wish to use one OBI for phones in my house and an outbuilding ~200 feet of wire will be required to reach the outbuilding. Will this impact the OBI's performance or possibly damage the power supply?

Time_Lord

highly doubtful... by the time you consider many people are using the device to power multiple phones within their homes, the wire runs can be quite long there too

-TL

Quintus

How about buying a spool of cat5 cable and custom cutting a 200 ft cat5 cable? Then you can attach an IP device in the outbuilding. That might mean buying a second obi device, but maybe that will work.

drgeoff

Quote from: Quintus on June 29, 2018, 12:15:30 AM
How about buying a spool of cat5 cable and custom cutting a 200 ft cat5 cable? Then you can attach an IP device in the outbuilding. That might mean buying a second obi device, but maybe that will work.
That is bad advice. The signals to and from a phone are much less demanding than those of ethernet, even 10 Mbit/s ethernet.

The signals between an OBi and phone are the same as between a phone and a telco local office. Many phones have more than 1 mile of wire to the local office.

200 ft of phone cable or even bell wire will be no problem for an OBi and phone. Plus it is cheaper than ethernet cable and being thinner is likely to be easier to install. No extra OBi or IP device needs to be bought.

zapattack

How many and what type of phones?
The Obi does not have the power of a telephone exchange to
ring multiple mechanical bell phones, but would be OK with
electronic sets.
The Obi default is 70V, whereas most exchanges put out closer to 100V.

Quintus

The signaling for phone wire is less demanding, but ethernet is a digital protocol. That digital protocol will resist noise. Also CAT5 cable has the twisted pair cabling which negates the need for shielding.

Personally, I don't know enough about longer lengths of phone cable. I took an undergrad class in networking basics, but I don't know the signal loss associated with types of cables. If the signal loss is small enough for 200 ft of phone cable, then you would be correct that phone cable is the superior solution.

I just had another thought. How would one prevent critters from biting into the cable? 200 ft is a long enough length that it becomes very concerning how one would protect from vermin. And if the cable does get bitten through, how would you splice the broken cable such that it is weatherproof? Again, I'm pleading ignorance. I simply don't have the experience in laying down cable.

Demos


Based on a Telcordia requirements that can be found in one of the Telcordia LSSGR documents, the ILEC (Telco), has to deliver supervisory DC current no less than 20ma @ -48VDC, to operate the transmitter and DTMF touch tone pad, and a minimum of 55VAC RMS to ring a maximum of four C4 Type mechanical ringers delivered at the DEMARC. Not all electronic ringers are equal. Look at the Ringer Equivalency designation on a telephone, as required by the FCC since 1979.

A Typical TelCo 2W POTS loop is designed for a maximum 1300 Ohms, and 8.5 dB of loss. Something that the OBI ATA's will certainly not meet. However I suspect that an OBI ATA's will work out on a two wire loop of no more than 200 Ohms. More than likely equal to a Part 68 OL-13A registered PBX port.

The bigest potential trouble will be noise on a long two wire connecting loop to an OBI ATA due to power influence inductance. Using CAT5/6 cable to extend the OBI200 FXS port should work well. Just be careful with the total number of the number of ringers attached to the line.