I'm having an amphenol 50 pin RJ-21 cable made by a cable manufacture. I sent them the pinout requirments from this URL http://www.cisco.com/en/US/docs/routers/access/vg224/hardware/installation/guide/higcabl.html#wp1043178
The cable manufacutre came back with a question regarding the pinout requirments. They want to know why they are asking for pin's 25, 50, 51, 52 to go to GND. Specifically 51 and 52 because they don't exist in a 25 pair cable.
Long time my friend :) These Pins/Pairs will not go to Ground. They are completely unused. I'm guessing this diagram was copied from some other reference.
Just a plain old RJ21 (Male) like this;
Cisco RJ21 Cables
Hope this helps!