Manual frequency select (US range)

[IFomin]

Hi, All.
It's my first message here, so be polite please.
For some purposes I need cell phone, witch could manually select frequency range(850 or 1900). It means if I select cell phone to work in 850 range it must not transmit in 1900 range and vice versa. I am ready to work with new or used cell phone. I just need to know the model if exist.

Thank you!