Here is the connector it has to go into.I found three other cable sites with the identical page you shared (but came up much more quickly).
Certainly looks like MMJ to me. that was what I searched for as well. http://www.pacificcable.com/photos/PT-J250-6DEC.jpg thanks jim On 4/8/2017 11:54 AM, Gregory Beat via cctalk wrote:
Paul, Are these the "offset clip" RJ-12 6p6c modular jacks? https://www.showmecables.com/dec-rj12-6p6c-modular-plug-flat-cable greg chicago Sent from iPad Air