50 multi-kills with claymores, frags, rpg, and/or c4
this website tells you how how to get all the emblems
if u have ps3 add ownupwnu69 for mw2
http://callofduty.wikia.com/wiki/Callsigns
By getting into a tenth prestige lobby.
go to http://callofduty.wikia.com/wiki/Callsigns
Yes you lose everything but titles and emblems
1000 kills with it ,tactical knife doesn't count.
heres one with emblems and titiles http://www.se7ensins.com/forums/modern-warfare-2-discussion/156442-callsigns-and-emblems-pic-list.html and heres how to get them http://www.se7ensins.com/forums/modern-warfare-2-discussion/156444-callsigns-and-get-them.html
They can be found at the Call of Duty wikia. A link has been added under related links
Theres no need to prestige unless you want the extra tittles and emblems on mw2.
Well, it depends. You only get titles and emblems if you do certain things. For example, you use stopping power a lot. Finally you get the emblem for it. You could just get a few emblems and still be a level 70. It depends on what you do.
no. for prestiging you only unlock new titles/emblems extra custom classes and a new symbol.
You get the ability to unlock more titles, emblems and challenges even for guns The bad thing is you'll lose all your camos, guns and xp