Help: bead and choke

Could you let me hnow the difference between bead and choke? How to select a bead for designning a GSM phone?

Choke is a folk name for an inductance used to stop signal currents. It generally depends only upon inductance.

A bead is a ferrite material with a hole through it for the wire. It acts like an inductor at low frequencies and at high frequencies an inductor in series with a resistor. This extra resistive loss works better than a pure inductor at stopping signal currents and prevent resonances in the filtering circuit which would make it work less effectively at the resonant frequencies.

Both are inductors.

For selection of choke, we should need to define the electric current through it!

For selection of bead, we should need to define the frequency of use!