What RJ11 Cables Should I Use?

Applications IP Networking
1

Hello All,

I have a project I'm working on which involves a linux PC and a USB (*dialup) Modem in a remote location for telnet'ing to that
PC by phone when the Ethernet connection is down.

I have already purchased the USB modems I need and some dumb phones for line testing... Now I'm trying to figure out
which RJ11 cables I should be using for this. Looking around online I have seen RJ11 cables with 2 and 4 pins/connectors.

The USB Modem's came with a 2 pin RJ11 cable, but the USB Modem itself, if you look inside the RJ11 port on the modem,
it has 4 copper "pins/connectors".

So can anyone recommend what RJ11 cables I should be getting for this? I wasn't sure if I would get any kind of speed or
performance increase if I used the 4 connector one instead of the 2?

I believe my choices are: 6P2C or 6P4C

Any suggestions would be greatly appreciated..!

FYI : And in case it's relevant the USB Modems I purchased are the Zoom 56K External USB Modem (Model 3095). See it
here --> Zoom Telephonics - V.92 56K USB Mini External Modem

Thanks in Advance,
Matt

2

The middle two conductors are the usual pair your telephone uses. The rest would be used to carry other telephone lines if you had more.

So, just about anything should work if you only care about the first telephone line.

1 Like
3

The answer to this question depends on which country you are in and the standards used by that country.

In the UK (where I am) the line from the telephone company is two core and this (normally) connects directly to the master (first) telephone socket on the premises. If there are second and more handsets on the line then four cores go on from this master socket to the second and subsequent sockets. One of these extra cores carries the 'ring' signal.

So, if you are only dealing with master sockets then two core RJ11 will be fine, but if you were plugging a modem into an extension socket it should still work but may NOT see an in-bound ring signal (assuming the Zoom modems are working to that country standard too).

Buying 4-core RJ11 is the safe option as extraneous cores would simply not be used on a master socket connection.

Hope that helps.

1 Like
4

Hey Guys, thanks for the replies!

Ok, great information, thank you! I think I'll go for the 4 then...

I'm not positive of the exact placement, but I believe it will be something like this:

Incoming TelCo Line ----cable---->2-Way Splitter----->1 cable to GW & 1 cable to USB Modem.
*SEE IMAGE BELOW...

    [IMG]http://i1326.photobucket.com/albums/u658/mrm5102/Diagram_zps3171fee3.jpg[/IMG]

Thanks again for the replies, much appreciated!

Thanks,
Matt

5

Presumably the cisco router also has a modem?

6

Yes, it has FXS and FXO ports for analog voice/phone system.

-Matt

---------- Post updated at 12:58 PM ---------- Previous update was at 11:27 AM ----------

Well I just purchased the 6 wire RJ12 cables. The only reason I got these was because they were less expensive then 4 and 2 wire cables on other sites.

Thanks for the help guys....

-Matt

7

It's pretty hard to go wrong with a telephone cable. Good luck.

8

Yea, I hear that... Thanks again!

-Matt