DiapDialer seems to recommend using the newest sip, 6.x. If such requires some other changes, I do not know. Or any benefits, I’m not familiar enough with to comment. Since you’re sticking with 4.x, I’ll go with that. For the moment, getting it to build without too much extra effort is preferable.
I’ll give it a try either later today or soon after. Seems like it should go ok this time, as you’ve already done it.