Bell Dataphone 303

Hello. I am searching for documentation about the Bell 303 Modem. This is referenced in some documents like a "Bell Datastation 303", but others mention the "Bell Dataphone 303". In the few images available, I can see the Modem cabinet with one Dataphone over it. My interest for this item is related with my searching of information about the early Arpanet. Every IMP could get connected up to FOUR Bell 303, connected every one to Wideband lines. Now I should like to learn how the Modem's side worked in terms of operation (protocol to establish connections between modems, manual operations, lights, sounds and other indicators of these devices, etc). I should agree to obtain any help, information and manual available about this matter. Thanks in advance Sergio