From Halopedia, the Halo wiki
Kari Wahlgren (born July 13, 1977) is an American voice actress. A few of her credits include Phineas & Ferb, Kung Fu Panda: Legends of Awesomeness, Fish Hooks, Blood+, Final Fantasy XII, and Lucky Star.
4orty2wo Entertainment contracted Wahlgren for their viral "I Love Bees" campaign for Halo 2. She played the voice of Janissary James throughout that series. Wahlgren returned in Halo 4 as the Ivanoff Station system voice.