# Cross-Hospital Communication
Cross-hospital communication involves information sharing among multiple sites or institutions. There are two main ways to set up communication between two locally separated networks of different sites. dot.base has a Web-User-Interface and is therefore ideal for cross-hospital communication from a technical standpoint. Working with medical data requires high standards of data protection. Legal issues need to be clarified first in the specific use case before implementing data sharing across institutions. If an individual patient consent is needed for the particular data sharing scenario, dot.base is capable of managing access control to medical data on a single patient level for every user.
As a secure communication channel is mandatory for communication with a remote site, dot.base is primarily intended to be accessed via restricted access networks for the healthcare sector. Within Germany, dot.base can be accessed via the national healthcare network "Telematik-Infrastruktur" by healthcare institution connected via the mandatory hardware device ("Konnektor"). A dot.base instance can be connected to the Telematik-Infrastruktur via the "aAdG-NetG" protocol, which allows HTTPS-communication in the Telematik-Infrastruktur network.
There are two different ways to implement cross-hospital communication which may apply depending on your specific needs.
# One dot.base instance for multiple sites
This solution is intended for medical collaborators like doctor's offices and smaller hospitals, who have some commonly treated patients with a medical center using dot.base. The primary benefit in this use case is to get access to the records from previous treatments at the center and to document own visits in a convenient way. Usually, doctor's offices do not have the capabilities to deploy and maintain an own dot.base instance.
For this use case, two separate FHIR-servers within the dot.base instance hosted in the center are generated. These FHIR-servers keep core data (name, DOB, address) and medical data for the collaborator separately from the center's (or other collaborator's) FHIR-server. The dot.base instance in the center can be accessed via the aforementioned secure connection. Authorization for collaborators is provided by the identity provider of the dot.base instance (Keycloak). Via the UI collaborators can access medical information on their own FHIR-servers and some FHIR-servers with medical data of the center. Which medical data can be accessed by collaborators depends on the individual user roles and permission in the dot.base instance and patients' consents.
# Multiple dot.base instances in different sites
This solution is intended for the collaboration between large institutions (e.g. university hospitals) that each maintain a dot.base instance in their IT-infrastructure. At the moment this feature is still on the roadmap, but it will be implemented in the future.