Rj48 Cable


Hello all,

Any one know if I need an rj48 straight through or crossover when setting up an HA100 with two UCM6510?



I don’t know HA100, but I think I read somewhere that the harness is a normal LAN connection


I guess that depends on if using SIP and/or PRI. If PRI, use RJ48 as it should have shielding and uses more pins for TX/RX as well as grounds. It is essentially wired the same as an Ethernet cable in that 8 conductors are in use, but the data rates are slower and one is typically UTP while the other is STP. The PRI provider might/should have provided a cable.


The PRI provider has provided a cable from their equipment to the HA100 but I need two more to go from the HA100 to the 6510s.




I agree that Amazon will likely have the product, it was while I was shopping, I found straight through and cross over cables.

I’m not sure which to use. Manual didn’t say.


You could ohm out the cable and HA and then…order straight thru, which is what most will require. x-over is usually needed when connecting two of the same device types.


There is nothing stopping you from plugging an RJ45 network cable into a PRI RJ48 jack (assuming you don’t have an RJ48…something [RJ48X maybe?] jack with blocking tabs on it. Most don’t). For normal use, you can substitute a STP network cable. Crossover not required with any modern device made after circa 2000.


So, it turns out my ignorance knows few bounds. As @SmartVox said and as I’ve confirmed with other sources, an RJ45 will work perfectly well as a RJ48. Apparently the keyed bit was a standard that hasn’t been used for 10 to 15 years.

If anyone knows different, please tell me. I’ve got an install coming in the next week or two and I’d like it to go as smoothly as possible.


Well, it appears that, based on new information, that we should be using a T1 cross over cables from the service providers equipment to the HA100. I’m not yet sure if I can use standard patch cables from the HA100 to the 6510’s.

Looking at the following GS document…

It states and shows the need for a cross over cable.

I’m confused and looking forward to your comments.

Thanks in advance.


Ha is straight as fair remember - i just used normal RJ-45 when tested with E1.


I guess your best bet is to get both straight and crossover and eliminate the issue. The cost of time in trying to figure it out and still possibly getting it wrong it not worth it. You could use a straight RJ45 for the beginning to minimize the expense, and a 48 x’over, but I suggest a true 48 when the dust is settled. As I noted, the electrical signaling characteristics are different between Ethernet and E1/T1 and the 48 is shielded against EMI. While a 45 may very well be just fine, I look at it as insurance against any future issues that might require a service call involving same. The cost of getting the spec’ed cable and knowing it is right is less than the cost of my time should it pose an issue down the line. Just my opinion.


Most people should use an OEM replacement battery for their electronic device (phone, tablet, Walkman, whatever). Most people use whatever’s cheapest. Same here.

You can usually get away with an STP RJ45 wired network cable for most T1/PRI work. Your mileage may vary and you SHOULD use a properly wired RJ48 cable. MOST plug electronics will auto-sense whether they need crossover or not. Your mileage may vary. If you have a crimper, a connector, and an existing cable, you can make your own if you can read wiring diagrams (see https://en.wikipedia.org/wiki/Crossover_cable). Or you can buy one for US$12 at Amazon (https://www.amazon.com/Tripp-Lite-Shielded-Cross-over-N266-005/dp/B0029LABD4).

We don’t have an HA100 so we can’t confirm or deny its functionality with different cable types and wiring, so your mileage may vary.

Did I mention that your mileage may vary? :slight_smile:


True, if the device is MDI/MDX sensing, but who knows about the HA? The spec sheet makes no mention. I have HA’s in use, but not with T1, only SIP. For $12, its a no brainer to me; not much more than the cost of a decent 6 pack of imported beer. I don’t like cheap, taste bad beer or cables that leave a bad taste later.


$12 has become almost as much as the cost of a decent NON imported beer. :slight_smile:


True dat.


Terrible expensive beer :stuck_out_tongue:
I do not think that 1m not shielded cable really is so bad :slight_smile: HA must be close to both UCM anyway.


Hello All,

Install of the 2 - 6510’s with the HA100 was delayed for a while. Thankfully I was paid in advance! Regardless, I wanted to let you know the results.

Direct from the PRI box, I could use a standard Ethernet cable to a 6510.

Moving the ethernet cable from the 6510 to the HA100 then connecting from the HA100 to the 6510 with a second ethernet cable failed.

Making up a couple patch cables, following the pin out in the diagram I’ve attached previously, worked great.

Confirming I had not messed up somehow, I swapped back to the ethernet cable and the PRI failed again.

So, if you’re using the HA100, you cannot use standard ethernet cables from the HA100 to the 6510.



Thanks for following up with this!


Well you need correctly cross cable as far i know.
U can use Ethernet cable but ISDN use different crossing).
I do it on etherent which i manually crossed.