Smartphone Traders are nothing more than common thieves. They use the classic "bait and switch" tactic by luring you with promises of the high prices they will pay for your phones. Then, once they have your phone in their possession, they determine that they cannot pay what they promised and proceed to offer you a ridiculously low amount. If you try to get your phone back and not accept their offer, they will give you a littany of excuses as to why they cannot return your phone.
Do not use these thieves!