diff --git a/grpc_server.go b/grpc_server.go
index 236467d..0e1d30e 100644
--- a/grpc_server.go
+++ b/grpc_server.go
@@ -55,6 +55,14 @@ func init() {
 	GrpcServerId = hex.EncodeToString(md.Sum(nil))
 }
 
+type GrpcServerHub interface {
+	GetSessionByResumeId(resumeId string) Session
+	GetSessionByPublicId(sessionId string) Session
+	GetSessionIdByRoomSessionId(roomSessionId string) (string, error)
+
+	GetBackend(u *url.URL) *Backend
+}
+
 type GrpcServer struct {
 	UnimplementedRpcBackendServer
 	UnimplementedRpcInternalServer
@@ -66,7 +74,7 @@ type GrpcServer struct {
 	listener net.Listener
 	serverId string // can be overwritten from tests
 
-	hub *Hub
+	hub GrpcServerHub
 }
 
 func NewGrpcServer(config *goconf.ConfigFile) (*GrpcServer, error) {
@@ -131,7 +139,7 @@ func (s *GrpcServer) LookupSessionId(ctx context.Context, request *LookupSession
 	statsGrpcServerCalls.WithLabelValues("LookupSessionId").Inc()
 	// TODO: Remove debug logging
 	log.Printf("Lookup session id for room session id %s", request.RoomSessionId)
-	sid, err := s.hub.roomSessions.GetSessionId(request.RoomSessionId)
+	sid, err := s.hub.GetSessionIdByRoomSessionId(request.RoomSessionId)
 	if errors.Is(err, ErrNoSuchRoomSession) {
 		return nil, status.Error(codes.NotFound, "no such room session id")
 	} else if err != nil {
@@ -221,7 +229,7 @@ func (s *GrpcServer) GetSessionCount(ctx context.Context, request *GetSessionCou
 		return nil, status.Error(codes.InvalidArgument, "invalid url")
 	}
 
-	backend := s.hub.backend.GetBackend(u)
+	backend := s.hub.GetBackend(u)
 	if backend == nil {
 		return nil, status.Error(codes.NotFound, "no such backend")
 	}
@@ -233,13 +241,18 @@ func (s *GrpcServer) GetSessionCount(ctx context.Context, request *GetSessionCou
 
 func (s *GrpcServer) ProxySession(request RpcSessions_ProxySessionServer) error {
 	statsGrpcServerCalls.WithLabelValues("ProxySession").Inc()
-	client, err := newRemoteGrpcClient(s.hub, request)
+	hub, ok := s.hub.(*Hub)
+	if !ok {
+		return status.Error(codes.Internal, "invalid hub type")
+
+	}
+	client, err := newRemoteGrpcClient(hub, request)
 	if err != nil {
 		return err
 	}
 
-	sid := s.hub.registerClient(client)
-	defer s.hub.unregisterClient(sid)
+	sid := hub.registerClient(client)
+	defer hub.unregisterClient(sid)
 
 	return client.run()
 }
diff --git a/hub.go b/hub.go
index 5684f3c..77a86c7 100644
--- a/hub.go
+++ b/hub.go
@@ -38,6 +38,7 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"net/url"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -623,6 +624,10 @@ func (h *Hub) GetSessionByResumeId(resumeId string) Session {
 	return session
 }
 
+func (h *Hub) GetSessionIdByRoomSessionId(roomSessionId string) (string, error) {
+	return h.roomSessions.GetSessionId(roomSessionId)
+}
+
 func (h *Hub) GetDialoutSession(roomId string, backend *Backend) *ClientSession {
 	url := backend.Url()
 
@@ -641,6 +646,10 @@ func (h *Hub) GetDialoutSession(roomId string, backend *Backend) *ClientSession
 	return nil
 }
 
+func (h *Hub) GetBackend(u *url.URL) *Backend {
+	return h.backend.GetBackend(u)
+}
+
 func (h *Hub) checkExpiredSessions(now time.Time) {
 	for session, expires := range h.expiredSessions {
 		if now.After(expires) {