I found it in AIM (of course!) here: 4-2-3 d. 2 (the example)
Thanks!2. At times, a controller/specialist may be working a sector with multiple frequency assignments. In order to eliminate unnecessary verbiage and to free the controller/specialist for higher priority transmissions, the controller/specialist may request the pilot “(Identification), change to my frequency 123.4.” This phrase should alert the pilot that the controller/specialist is only changing frequencies, not controller/specialist, and that initial callup phraseology may be abbreviated.
EXAMPLE-
“United Two Twenty-Two on one two three point four” or “one two three point four, United Two Twenty-Two.”
Doug