Signal problem. i dont mean to sound like a moron. but i bought a new unlocked phone off ebay it

Question

i dont mean to sound like a moron. but i bought a new unlocked phone off ebay it says its a wq n95. its reading the sims card fine but it wont get signal i dont think its connecting with at&t. so i need to know how to tell and how to fix it. because it came from hong kong and im clueless.