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Community Member

pin order of CAB-E1-PRI

I fill annoyed by the cable CAB-E1-PRI (if I am not wrong, this cable is used for ISDN connection. One end is a RJ-45 connector to plug into Telecom's CPE. The other end is a DB-15 connector to match the PRI port on my NM-1CE1B module of the 2621 router.)

My quetion is: what is the signal definition on the pins of the RJ-45 and the DB15 connectors? I found two documents in CISCO's web site about the RJ-45 connector. One said that pin 1 is for Receive Tip, and pin 2 for Receive ring, and pin 3 for Transimit Tip, and pin 4 for Tx ring. The other said that pin 1 is for Transmit tip, and pin 2 for Tx ring, and pin3 for Receive tip, and pin 4 for Rx ring. Which one is right?

By the way, what is the meaing of "ring" and "tip"? And what is the difference between E1 and ISDN PRI?

Thank you!


Re: pin order of CAB-E1-PRI


Regarding pinouts - best bet is to confirm with your network provider as there are a couple of options depending on service and location.

If you're interesting in the signalling (tip/ring/etc.) then Cisco has a good paper on this here:

Also, E1 and ISDN PRI are different standards for different applications.



Community Member

Re: pin order of CAB-E1-PRI

Hi, Andrew

Thank you for your quick response and the useful link. I am reading this article carefully.

My trouble is: I don't know the signal deffinition on the RJ-45 end, so I don't know how to match the connector that the telecom left for me. If I know what each pin means, I will order him to make a connector in a right pin sequence.

By the way, what does HTH mean?


Re: pin order of CAB-E1-PRI


I'd use the original reference for pinouts, here:

Newer versions of this network module introduced additional options but you should be safe with this.

HTH means "hope that helps"


plz rate useful posts!

Community Member

Re: pin order of CAB-E1-PRI


As you Hope, That answer is extremely Helpful.

Thank you very much!

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