multiple GSM devices(transceivers)sharing only one antenna

Hello everyone,

Is it possible for a group of GSM mobile devices(transceivers of course) to share one GSM antenna. I have heard that similar devices exist, but on the other hand how do they prevent permanent damage of the receivers inputs during transmission phases of other GSM devices connected to the same antenna. Is this really possible and are some collisions present on the GSM antenna?Are these devices active or passive devices? Which companies are producing these kind of devices if they really exist?


Thanks.