"When you first start out you only have a few titles and emblems," Bowling told MTV News. New titles and emblems will appear according to weapon usage, in-game actions and rank.

   "As you rank up, you automatically get a new title. Llike I’m a sergeant, now I have a Sergeant title. But now say, when I was ranking up I only used pistols, so now you’ll not only get icons for your rank, you’ll also get titles and emblems that are pistol-focused."

Read more here:
http://multiplayerblog.mtv.com/2009/09/18/call-of-duty-modern-warfare-2-infinity-ward-talks-callsigns-and-community/

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