The facility will either approve or deny your request depending on workload and coverage:
"OE-CMV, radar service approved. Squawk two-three-zero-zero."
"OE-CMV, radar service not available at this time. Continue with FIS."
When radar service is approved, you will be assigned a squawk code. Set the code, read it back, and await radar contact. Once the facility has you on radar, they will confirm:
"OE-CMV, radar contact, ten miles south of Linz, flight level one-zero-five."
This confirmation tells you that the facility now has you identified on the radar screen and will provide you with radar information.