Depends if you are talking about a Traffic call or a Traffic alert, they are two separate things essentially.
Also with Merging Target procedures we are required in certain cases to issue traffic calls when targets (RADAR Targets) appear likely to merge and the aircraft are only separated by the minimum allowed (ie 1000 ft)
A traffic alert will ALways be proceeded with the Phrase "Traffic Alert"
Example "TRAFFIC ALERT, November-Four-Golf-Aplha, TRAFFIC twelve o'clock, less than a mile, oposite direction, Advise you turn right heading Three-Six-Zero IMMEDIATELY."
A traffic call is slightly more casual.
"November-Four-Golf-Alpha, traffic two o'clock, 6 miles, southbound, converging, Dash-Eight, Four thousand descending to Three Thousand."