Does Sabre , Ameadeu , Applo , worldspan have communication ability amongst each other.They communicate and trasfer data amongst themselves.

I understand the the airlines are loyal to one GDS. But what about Hotels. Hotels would like to list there property on all GDS and would want all the GDS to be able to manage there room reservations. For that it will be necceary to ensure that the room count(occupied) is shared

Cheers
- Puneet