Your phoneline voltage measurements are typical, so not likely to be the problem with dialing out. You also get dialtone when you take you house phone off hook so the phone company is happy with your line conditions.
I connected the RJ31X directly to the Elk eliminating the RJ45 plug/cable. Problem solved. Bad RJ45 plug/cable? I went by the RJ31X RJ45 cable color description on page 7 of the installation manual. I assume that is correct. Elk dialer now working fine.