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Can I use CAT 5 cable instead of RJ-48?

Hi, I need to connect a Cisco UC560 to a BT ISDN 30 circuit.  I am having problems getting it to work and althrough a RJ45 cable works fine, others seem to infer that I need a RJ58 cable however there seems confusion from others as to whether the RJ45 wiring will work fine in place of the RJ58.
Any ideas??

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8/22/2022 - Mon

RJ-45 only one has 1 data line where RJ-48 has 4, so it may work but may not work at its full capacity. RJ-48 is used for T1 and ISDN termination. It uses the same 8 position connector as RJ-45 but is wired differently. Here's a wiki article that shows the wiring so you can make your own rj-48s cable.

Thanks so you agree CAT 5 should work then it is fault elsewhere I need to investigate?

From what I can find on the UC560 it's recommended to use RJ-48 for T1 and ISDN. RJ-48 use the same cable(cat5, cat5e, or cat6) and ends(8p8c modular plug) as RJ-45 but RJ-48 is wired differently. Since you are having problems getting it to work properly you should try the recommended cable.
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Correct and proven, phone system all working fine using CAT 5 cable, that's all I wanted to know.