diff --git a/agents/diamagent.go b/agents/diamagent.go
index 5dd16e6d8..422732721 100644
--- a/agents/diamagent.go
+++ b/agents/diamagent.go
@@ -36,11 +36,11 @@ import (
 )
 
 func NewDiameterAgent(cgrCfg *config.CGRConfig, filterS *engine.FilterS,
-	sessionS rpcclient.RpcClientConnection) (*DiameterAgent, error) {
-	if sessionS != nil && reflect.ValueOf(sessionS).IsNil() {
-		sessionS = nil
+	sS rpcclient.RpcClientConnection) (*DiameterAgent, error) {
+	if sS != nil && reflect.ValueOf(sS).IsNil() {
+		sS = nil
 	}
-	da := &DiameterAgent{cgrCfg: cgrCfg, filterS: filterS, sessionS: sessionS}
+	da := &DiameterAgent{cgrCfg: cgrCfg, filterS: filterS, sS: sS}
 	dictsPath := cgrCfg.DiameterAgentCfg().DictionariesPath
 	if len(dictsPath) != 0 {
 		if err := loadDictionaries(dictsPath, utils.DiameterAgent); err != nil {
@@ -61,15 +61,16 @@ func NewDiameterAgent(cgrCfg *config.CGRConfig, filterS *engine.FilterS,
 			procsr.ReplyFields = tpls
 		}
 	}
+	//da.sS.SetClientConn(da) // pass the connection to sessionS back so we can receive the disconnects
 	return da, nil
 }
 
 type DiameterAgent struct {
 	cgrCfg   *config.CGRConfig
 	filterS  *engine.FilterS
-	sessionS rpcclient.RpcClientConnection // Connection towards CGR-SessionS component
+	sS       rpcclient.RpcClientConnection // Connection towards CGR-SessionS component
 	aReqs    int
-	sync.RWMutex
+	aReqsLck sync.RWMutex
 }
 
 // ListenAndServe is called when DiameterAgent is started, usually from within cmd/cgr-engine
@@ -160,7 +161,7 @@ func (da *DiameterAgent) handleMessage(c diam.Conn, m *diam.Message) {
 		return
 	}
 	if da.cgrCfg.DiameterAgentCfg().MaxActiveReqs != -1 {
-		da.Lock()
+		da.aReqsLck.Lock()
 		if da.aReqs == da.cgrCfg.DiameterAgentCfg().MaxActiveReqs {
 			utils.Logger.Err(
 				fmt.Sprintf("<%s> denying request due to maximum active requests reached: %d, message: %s",
@@ -169,11 +170,11 @@ func (da *DiameterAgent) handleMessage(c diam.Conn, m *diam.Message) {
 			return
 		}
 		da.aReqs++
-		da.Unlock()
+		da.aReqsLck.Unlock()
 		defer func() { // schedule decrement when returning out of function
-			da.Lock()
+			da.aReqsLck.Lock()
 			da.aReqs--
-			da.Unlock()
+			da.aReqsLck.Unlock()
 		}()
 	}
 	rply := config.NewNavigableMap(nil) // share it among different processors
@@ -266,7 +267,7 @@ func (da *DiameterAgent) processRequest(reqProcessor *config.DARequestProcessor,
 			reqProcessor.Flags.HasKey(utils.MetaSuppliersEventCost),
 			*cgrEv)
 		var authReply sessions.V1AuthorizeReply
-		err = da.sessionS.Call(utils.SessionSv1AuthorizeEvent,
+		err = da.sS.Call(utils.SessionSv1AuthorizeEvent,
 			authArgs, &authReply)
 		if agReq.CGRReply, err = NewCGRReply(&authReply, err); err != nil {
 			return
@@ -279,7 +280,7 @@ func (da *DiameterAgent) processRequest(reqProcessor *config.DARequestProcessor,
 			reqProcessor.Flags.HasKey(utils.MetaThresholds),
 			reqProcessor.Flags.HasKey(utils.MetaStats), *cgrEv)
 		var initReply sessions.V1InitSessionReply
-		err = da.sessionS.Call(utils.SessionSv1InitiateSession,
+		err = da.sS.Call(utils.SessionSv1InitiateSession,
 			initArgs, &initReply)
 		if agReq.CGRReply, err = NewCGRReply(&initReply, err); err != nil {
 			return
@@ -289,7 +290,7 @@ func (da *DiameterAgent) processRequest(reqProcessor *config.DARequestProcessor,
 			reqProcessor.Flags.HasKey(utils.MetaAttributes),
 			reqProcessor.Flags.HasKey(utils.MetaAccounts), *cgrEv)
 		var updateReply sessions.V1UpdateSessionReply
-		err = da.sessionS.Call(utils.SessionSv1UpdateSession,
+		err = da.sS.Call(utils.SessionSv1UpdateSession,
 			updateArgs, &updateReply)
 		if agReq.CGRReply, err = NewCGRReply(&updateReply, err); err != nil {
 			return
@@ -301,7 +302,7 @@ func (da *DiameterAgent) processRequest(reqProcessor *config.DARequestProcessor,
 			reqProcessor.Flags.HasKey(utils.MetaThresholds),
 			reqProcessor.Flags.HasKey(utils.MetaStats), *cgrEv)
 		var tRply string
-		err = da.sessionS.Call(utils.SessionSv1TerminateSession,
+		err = da.sS.Call(utils.SessionSv1TerminateSession,
 			terminateArgs, &tRply)
 		if agReq.CGRReply, err = NewCGRReply(nil, err); err != nil {
 			return
@@ -315,7 +316,7 @@ func (da *DiameterAgent) processRequest(reqProcessor *config.DARequestProcessor,
 			reqProcessor.Flags.HasKey(utils.MetaStats),
 			*cgrEv)
 		var eventRply sessions.V1ProcessEventReply
-		err = da.sessionS.Call(utils.SessionSv1ProcessEvent,
+		err = da.sS.Call(utils.SessionSv1ProcessEvent,
 			evArgs, &eventRply)
 		if utils.ErrHasPrefix(err, utils.RalsErrorPrfx) {
 			cgrEv.Event[utils.Usage] = 0 // avoid further debits
@@ -331,7 +332,7 @@ func (da *DiameterAgent) processRequest(reqProcessor *config.DARequestProcessor,
 	if reqProcessor.Flags.HasKey(utils.MetaCDRs) &&
 		!reqProcessor.Flags.HasKey(utils.MetaDryRun) {
 		var rplyCDRs string
-		if err = da.sessionS.Call(utils.SessionSv1ProcessCDR,
+		if err = da.sS.Call(utils.SessionSv1ProcessCDR,
 			cgrEv, &rplyCDRs); err != nil {
 			agReq.CGRReply.Set([]string{utils.Error}, err.Error(), false, false)
 		}
@@ -353,3 +354,19 @@ func (da *DiameterAgent) processRequest(reqProcessor *config.DARequestProcessor,
 	}
 	return true, nil
 }
+
+// rpcclient.RpcClientConnection interface
+func (da *DiameterAgent) Call(serviceMethod string, args interface{}, reply interface{}) error {
+	return utils.RPCCall(da, serviceMethod, args, reply)
+}
+
+// V1DisconnectSession is part of the sessions.SessionSClient
+func (da *DiameterAgent) V1DisconnectSession(args utils.AttrDisconnectSession, reply *string) error {
+	return utils.ErrNotImplemented
+}
+
+// V1GetActiveSessionIDs is part of the sessions.SessionSClient
+func (da *DiameterAgent) V1GetActiveSessionIDs(ignParam string,
+	sessionIDs *[]*sessions.SessionID) error {
+	return utils.ErrNotImplemented
+}
diff --git a/agents/diamagent_test.go b/agents/diamagent_test.go
new file mode 100644
index 000000000..db1d741df
--- /dev/null
+++ b/agents/diamagent_test.go
@@ -0,0 +1,28 @@
+/*
+Real-time Online/Offline Charging System (OCS) for Telecom & ISP environments
+Copyright (C) ITsysCOM GmbH
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>
+*/
+package agents
+
+import (
+	"testing"
+
+	"github.com/cgrates/cgrates/sessions"
+)
+
+func TestDAsSessionSClientIface(t *testing.T) {
+	_ = sessions.SessionSClient(new(DiameterAgent))
+}
diff --git a/cmd/cgr-engine/cgr-engine.go b/cmd/cgr-engine/cgr-engine.go
index 5fa19269d..607d996dc 100644
--- a/cmd/cgr-engine/cgr-engine.go
+++ b/cmd/cgr-engine/cgr-engine.go
@@ -333,20 +333,33 @@ func startAsteriskAgent(internalSMGChan chan rpcclient.RpcClientConnection, exit
 	exitChan <- true
 }
 
-func startDiameterAgent(internalSMGChan chan rpcclient.RpcClientConnection,
+func startDiameterAgent(internalSsChan chan rpcclient.RpcClientConnection,
 	exitChan chan bool, filterSChan chan *engine.FilterS) {
 	var err error
 	utils.Logger.Info("Starting CGRateS DiameterAgent service")
 	filterS := <-filterSChan
 	filterSChan <- filterS
-	var smgConn *rpcclient.RpcClientPool
-	if len(cfg.DiameterAgentCfg().SessionSConns) != 0 {
-		smgConn, err = engine.NewRPCPool(rpcclient.POOL_FIRST,
+	var sS rpcclient.RpcClientConnection
+	var sSInternal bool
+	if len(cfg.DiameterAgentCfg().SessionSConns) == 0 {
+		utils.Logger.Crit(
+			fmt.Sprintf("<%s> no SessionS connections defined",
+				utils.DiameterAgent))
+		exitChan <- true
+		return
+	}
+	if cfg.DiameterAgentCfg().SessionSConns[0].Address == utils.MetaInternal {
+		sSInternal = true
+		sSIntConn := <-internalSsChan
+		internalSsChan <- sSIntConn
+		sS = utils.NewBiRPCInternalClient(sSIntConn.(*sessions.SMGeneric))
+	} else {
+		sS, err = engine.NewRPCPool(rpcclient.POOL_FIRST,
 			cfg.TlsCfg().ClientKey,
 			cfg.TlsCfg().ClientCerificate, cfg.TlsCfg().CaCertificate,
 			cfg.GeneralCfg().ConnectAttempts, cfg.GeneralCfg().Reconnects,
 			cfg.GeneralCfg().ConnectTimeout, cfg.GeneralCfg().ReplyTimeout,
-			cfg.DiameterAgentCfg().SessionSConns, internalSMGChan,
+			cfg.DiameterAgentCfg().SessionSConns, internalSsChan,
 			cfg.GeneralCfg().InternalTtl)
 		if err != nil {
 			utils.Logger.Crit(fmt.Sprintf("<%s> Could not connect to %s: %s",
@@ -355,12 +368,15 @@ func startDiameterAgent(internalSMGChan chan rpcclient.RpcClientConnection,
 			return
 		}
 	}
-	da, err := agents.NewDiameterAgent(cfg, filterS, smgConn)
+	da, err := agents.NewDiameterAgent(cfg, filterS, sS)
 	if err != nil {
 		utils.Logger.Err(fmt.Sprintf("<DiameterAgent> error: %s!", err))
 		exitChan <- true
 		return
 	}
+	if sSInternal { // bidirectional client backwards connection
+		sS.(*utils.BiRPCInternalClient).SetClientConn(da)
+	}
 	if err = da.ListenAndServe(); err != nil {
 		utils.Logger.Err(fmt.Sprintf("<DiameterAgent> error: %s!", err))
 	}
diff --git a/config/config.go b/config/config.go
index 4bc83262a..b3d75d8a1 100755
--- a/config/config.go
+++ b/config/config.go
@@ -605,11 +605,13 @@ func (self *CGRConfig) checkConfigSanity() error {
 		}
 	}
 	// DAgent checks
-	if self.diameterAgentCfg.Enabled && !self.sessionSCfg.Enabled {
-		for _, daSMGConn := range self.diameterAgentCfg.SessionSConns {
-			if daSMGConn.Address == utils.MetaInternal {
-				return fmt.Errorf("%s not enabled but referenced by %s component",
-					utils.SessionS, utils.DiameterAgent)
+	if self.diameterAgentCfg.Enabled {
+		if !self.sessionSCfg.Enabled {
+			for _, daSMGConn := range self.diameterAgentCfg.SessionSConns {
+				if daSMGConn.Address == utils.MetaInternal {
+					return fmt.Errorf("%s not enabled but referenced by %s component",
+						utils.SessionS, utils.DiameterAgent)
+				}
 			}
 		}
 	}