This glenoidal component for a shoulder prosthesis comprises a base which may be immobilized on the glenoid cavity of a shoulder, and an element provided to be mounted on this base and forming a convex surface of articulation centered on an axis of symmetry. Four transistors, forming an H bridge, allow DC current to flow in both directions in the lifting magnet. In another embodiment, an outbound telephone number or other identifier is automatically selected when making an outbound telephone call or sending a message based on an association of that outbound telephone number with the intended recipient of the call or message.