You will also hear, up here in northern Ontario between Creebec air that flies to Moosonee CYMO, and Cree 649 and Cree136 (as an example) who fly in opposite directions. YOu'll hear : "Cree 136, traffic, opposite direction, 11 o'clock for 7 miles, 1000 feet above you, (aircraft type) is your company Cree649, and BREAK Cree 649, your opposite direction traffic is your company Cree136, 5 o'clock, 1000 feet below you (aircraft type) please report visual reference."
Sometimes, ATC will advise targets, with aircraft type, direction of flight, etc, but most times the altitude is unknown and remarked as unknown/unverified, be advised.