rj45 to rj11 for modem connection

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 Question by louis wood posted 18 Jan 2006
 rj45 to rj11 for modem connection

I have recently purchased a adsl2+ modem/router (us robotics usr9108). It was produced for the german market and the adsl socket for connecting the modem to the internet is rj45. It is also delivered with an rj45 cable.(apparently this is standard in germany). However i live in the UK and the standard here is rj11. My filtre which is uk standard only has a rj11 socket. I am therefore unable to connect the modem to the internet. (i read somewhere that u can plug an rj11 plug into an rj45 socket however when i tried this the modem could not connect to the internet). I have seen on the internet that cables are available that have a rj11 plug on one end and a rj45 plug on the other.
Would this enable me to connect my modem to the internet? Would this type of cable be able to transmit the same data to the same standard as a standard rj45 cable. Would it work at all or would there be a loss of speed/quality??

Thanks in anticipation
 Answer by Joseph Golan posted 18 Jan 2006
Dear Louis,

An RJ-11 is only a 1-pair plug and is typically connected to pins 4 & 5 on the RJ-45 side and pins 3 & 4 on the RJ-11 side.
In most cases you can use a standard 2 conductor telephone cord with RJ-11s on both ends as the RJ-11 centers and aligns this pair in the RJ-45.

However you mentioned that your are trying to use the filter for your modem. This is incorrect, the filter is only to be used on your analog telephone equipment (Telephone, answering machines, fax, etc.) If actually filter out the DSL signal which can sometime be heard as noise on your analog equipment. DO NOT USE THE FILTER for the inbound signal to your DSL modem/router.

Joseph Golan, RCDD

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