In a medium saucepan, bring the chicken, broth and 2 cups water to a simmer. Lower the heat, cover and simmer until the chicken is cooked through, 30 minutes. Remove the chicken; let cool. Shred the meat; reserve. Return the bones to the broth, bring to a boil and reduce by about one-third.
Strain the broth. Whisk the curry paste into the broth and return to a simmer over medium-high heat. Add the noodles and bell pepper and cook until the noodles are just tender, about 3 minutes. Stir in the chicken.
Ladle the soup into bowls and top with the scallions and cilantro leaves. Serve with the lime wedges.