Air carrier on approach to CLT described a confused transfer to the tower instruction from ATC; listing non standard ATC phraseology as a causal factor.

Narrative

During the approach to Runway 18C in CLT; about 20 miles out; we were given an approach clearance to 18C. At the end of the clearance the Controller said; maintain 170kts until OZEJI and contact Tower. The First Officer read back; maintain 170kts and contact Tower at OZEJI. As we were flying the approach; and about a mile or two out of OZEJI; the First Officer was about to contact Tower; then ATC queried us and the First Officer responded. Then ATC asked again 'Air Carrier X if you hear us IDENT and turn 270 degrees and climb to 4000' and we broke off the approach as requested. The First Officer responded again with the heading and altitude and an IDENT. Cause; the event occurred because CLT ATC is not standard in their phraseology and procedures. We understood and read back to maintain 170kts and contact Tower at OZEJI. CLT never has you switch to Tower 20 miles out on an approach and often has you wait until 5 miles or less to switch to Tower. Between the time ATC made this transmission to the time they gave us the missed instructions; there were about 15 miles. If they wanted us to switch to Tower right away; why hadn't they contacted us until right before OZEJI.