diff --git a/data/conf/samples/tutmysql_internal/cgrates.json b/data/conf/samples/tutmysql_internal/cgrates.json
new file mode 100644
index 000000000..e4a29daa8
--- /dev/null
+++ b/data/conf/samples/tutmysql_internal/cgrates.json
@@ -0,0 +1,289 @@
+{
+// CGRateS Configuration file
+//
+
+
+"general": {
+	"log_level": 7,
+},
+
+
+"listen": {
+	"rpc_json": ":2012",
+	"rpc_gob": ":2013",
+	"http": ":2080",
+},
+
+"data_db": {								// database used to store runtime data (eg: accounts, cdr stats)
+	"db_type": "redis",						// data_db type: <redis|mongo>
+	"db_port": 6379, 						// data_db port to reach the database
+	"db_name": "10", 						// data_db database name to connect to
+},
+
+"stor_db": {
+	"db_password": "CGRateS.org",
+},
+
+
+"cache":{
+	"destinations": {"limit": 10000, "ttl":"0s", "precache": true},
+	"reverse_destinations": {"limit": 10000, "ttl":"0s", "precache": true},
+	"rating_plans": {"limit": 10000, "ttl":"0s","precache": true},
+	"rating_profiles": {"limit": 10000, "ttl":"0s", "precache": true},
+	"actions": {"limit": 10000, "ttl":"0s", "precache": true},
+	"action_plans": {"limit": 10000, "ttl":"0s", "precache": true},
+	"account_action_plans": {"limit": 10000, "ttl":"0s", "precache": true},
+	"action_triggers": {"limit": 10000, "ttl":"0s", "precache": true},
+	"shared_groups": {"limit": 10000, "ttl":"0s", "precache": true},
+	"resource_profiles": {"limit": 10000, "ttl":"0s", "precache": true},
+	"resources": {"limit": 10000, "ttl":"0s", "precache": true},
+	"statqueues": {"limit": 10000, "ttl":"0s", "precache": true},
+	"statqueue_profiles": {"limit": 10000, "ttl":"0s", "precache": true},
+	"thresholds": {"limit": 10000, "ttl":"0s", "precache": true},
+	"threshold_profiles": {"limit": 10000, "ttl":"0s", "precache": true},
+	"filters": {"limit": 10000, "ttl":"0s", "precache": true},
+	"supplier_profiles": {"limit": 10000, "ttl":"0s", "precache": true},
+	"attribute_profiles": {"limit": 10000, "ttl":"0s", "precache": true},
+	"resource_filter_indexes" :{"limit": 10000, "ttl":"0s"},
+	"stat_filter_indexes" : {"limit": 10000, "ttl":"0s"},
+	"threshold_filter_indexes" : {"limit": 10000, "ttl":"0s"},
+	"supplier_filter_indexes" : {"limit": 10000, "ttl":"0s"},
+	"attribute_filter_indexes" : {"limit": 10000, "ttl":"0s"},
+	"charger_filter_indexes" : {"limit": 10000, "ttl":"0s"},
+},
+
+
+"rals": {
+	"enabled": true,
+	"thresholds_conns": [
+		{"address": "*internal"},
+	],
+},
+
+
+"scheduler": {
+	"enabled": true,
+	"cdrs_conns": [
+		{"address": "*internal"},
+	],
+},
+
+
+"cdrs": {
+	"enabled": true,
+	"chargers_conns":[
+		{"address": "*internal"},
+	],
+},
+
+
+"cdre": {
+	"TestTutITExportCDR": {
+		"content_fields": [
+			{"tag": "CGRID", "type": "*composed", "value": "~CGRID"},
+			{"tag": "RunID", "type": "*composed", "value": "~RunID"},
+			{"tag":"OriginID", "type": "*composed", "value": "~OriginID"},
+			{"tag":"RequestType", "type": "*composed", "value": "~RequestType"},
+			{"tag":"Tenant", "type": "*composed", "value": "~Tenant"},
+			{"tag":"Category", "type": "*composed", "value": "~Category"},
+			{"tag":"Account", "type": "*composed", "value": "~Account"},
+			{"tag":"Destination", "type": "*composed", "value": "~Destination"},
+			{"tag":"AnswerTime", "type": "*composed", "value": "~AnswerTime", "layout": "2006-01-02T15:04:05Z07:00"},
+			{"tag":"Usage", "type": "*composed", "value": "~Usage"},
+			{"tag":"Cost", "type": "*composed", "value": "~Cost", "rounding_decimals": 4},
+			{"tag":"MatchedDestinationID", "type": "*composed", "value": "~CostDetails:s/\"MatchedDestId\":.*_(\\w{4})/${1}/:s/\"MatchedDestId\":\"INTERNAL\"/ON010/"},
+		],
+	},
+},
+
+"loaders": [
+	{
+		"id": "TeoLoader",									// identifier of the Loader
+		"enabled": false,									// starts as service: <true|false>.
+		"dry_run": false,									// do not send the CDRs to CDRS, just parse them
+		"run_delay": 0,										// sleep interval in seconds between consecutive runs, 0 to use automation via inotify
+		"lock_filename": ".cgr.lock",						// Filename containing concurrency lock in case of delayed processing
+		"caches_conns": [
+			{"address": "*internal"},						// address where to reach the CacheS for data reload, empty for no reloads  <""|*internal|x.y.z.y:1234>
+		],
+		"field_separator": ",",								// separator used in case of csv files
+		"tp_in_dir": "/tmp/In",		// absolute path towards the directory where the CDRs are stored
+		"tp_out_dir": "/tmp/Out",	// absolute path towards the directory where processed CDRs will be moved
+		"data":[	
+			{
+				"type": "*resources",						// data source type
+				"file_name": "Resources.csv",				// file name in the tp_in_dir
+				"fields": [
+					{"tag": "Tenant", "field_id": "Tenant", "type": "*composed", "value": "~0", "mandatory": true},
+					{"tag": "ID", "field_id": "ID", "type": "*composed", "value": "~1", "mandatory": true},
+					{"tag": "FilterIDs", "field_id": "FilterIDs", "type": "*composed", "value": "~2"},
+					{"tag": "ActivationInterval", "field_id": "ActivationInterval", "type": "*composed", "value": "~3"},
+					{"tag": "TTL", "field_id": "UsageTTL", "type": "*composed", "value": "~4"},
+					{"tag": "Limit", "field_id": "Limit", "type": "*composed", "value": "~5"},
+					{"tag": "AllocationMessage", "field_id": "AllocationMessage", "type": "*composed", "value": "~6"},
+					{"tag": "Blocker", "field_id": "Blocker", "type": "*composed", "value": "~7"},
+					{"tag": "Stored", "field_id": "Stored", "type": "*composed", "value": "~8"},
+					{"tag": "Weight", "field_id": "Weight", "type": "*composed", "value": "~9"},
+					{"tag": "ThresholdIDs", "field_id": "ThresholdIDs", "type": "*composed", "value": "~10"},
+				],
+			},
+			{
+				"type": "*stats",						// data source type
+				"file_name": "Stats.csv",				// file name in the tp_in_dir
+				"fields": [
+					{"tag": "Tenant", "field_id": "Tenant", "type": "*composed", "value": "~0", "mandatory": true},
+					{"tag": "ID", "field_id": "ID", "type": "*composed", "value": "~1", "mandatory": true},
+					{"tag": "FilterIDs", "field_id": "FilterIDs", "type": "*composed", "value": "~2"},
+					{"tag": "ActivationInterval", "field_id": "ActivationInterval", "type": "*composed", "value": "~3"},
+					{"tag": "QueueLength", "field_id": "QueueLength", "type": "*composed", "value": "~4"},
+					{"tag": "TTL", "field_id": "TTL", "type": "*composed", "value": "~5"},
+					{"tag": "Metrics", "field_id": "Metrics", "type": "*composed", "value": "~6"},
+					{"tag": "MetricParams", "field_id": "Parameters", "type": "*composed", "value": "~7"},
+					{"tag": "Blocker", "field_id": "Blocker", "type": "*composed", "value": "~8"},
+					{"tag": "Stored", "field_id": "Stored", "type": "*composed", "value": "~9"},
+					{"tag": "Weight", "field_id": "Weight", "type": "*composed", "value": "~10"},
+					{"tag": "MinItems", "field_id": "MinItems", "type": "*composed", "value": "~11"},
+					{"tag": "ThresholdIDs", "field_id": "ThresholdIDs", "type": "*composed", "value": "~12"},
+				],
+			},
+			{
+				"type": "*thresholds",						// data source type
+				"file_name": "Thresholds.csv",				// file name in the tp_in_dir
+				"fields": [
+					{"tag": "Tenant", "field_id": "Tenant", "type": "*composed", "value": "~0", "mandatory": true},
+					{"tag": "ID", "field_id": "ID", "type": "*composed", "value": "~1", "mandatory": true},
+					{"tag": "FilterIDs", "field_id": "FilterIDs", "type": "*composed", "value": "~2"},
+					{"tag": "ActivationInterval", "field_id": "ActivationInterval", "type": "*composed", "value": "~3"},
+					{"tag": "MaxHits", "field_id": "MaxHits", "type": "*composed", "value": "~4"},
+					{"tag": "MinHits", "field_id": "MinHits", "type": "*composed", "value": "~5"},
+					{"tag": "MinSleep", "field_id": "MinSleep", "type": "*composed", "value": "~6"},
+					{"tag": "Blocker", "field_id": "Blocker", "type": "*composed", "value": "~7"},
+					{"tag": "Weight", "field_id": "Weight", "type": "*composed", "value": "~8"},
+					{"tag": "ActionIDs", "field_id": "ActionIDs", "type": "*composed", "value": "~9"},
+					{"tag": "Async", "field_id": "Async", "type": "*composed", "value": "~10"},
+				],
+			},
+			{
+				"type": "*suppliers",						// data source type
+				"file_name": "Suppliers.csv",				// file name in the tp_in_dir
+				"fields": [
+					{"tag": "Tenant", "field_id": "Tenant", "type": "*composed", "value": "~0", "mandatory": true},
+					{"tag": "ID", "field_id": "ID", "type": "*composed", "value": "~1", "mandatory": true},
+					{"tag": "FilterIDs", "field_id": "FilterIDs", "type": "*composed", "value": "~2"},
+					{"tag": "ActivationInterval", "field_id": "ActivationInterval", "type": "*composed", "value": "~3"},
+					{"tag": "Sorting", "field_id": "Sorting", "type": "*composed", "value": "~4"},
+					{"tag": "SortingParamameters", "field_id": "SortingParamameters", "type": "*composed", "value": "~5"},
+					{"tag": "SupplierID", "field_id": "SupplierID", "type": "*composed", "value": "~6"},
+					{"tag": "SupplierFilterIDs", "field_id": "SupplierFilterIDs", "type": "*composed", "value": "~7"},
+					{"tag": "SupplierAccountIDs", "field_id": "SupplierAccountIDs", "type": "*composed", "value": "~8"},
+					{"tag": "SupplierRatingPlanIDs", "field_id": "SupplierRatingPlanIDs", "type": "*composed", "value": "~9"},
+					{"tag": "SupplierResourceIDs", "field_id": "SupplierResourceIDs", "type": "*composed", "value": "~10"},
+					{"tag": "SupplierStatIDs", "field_id": "SupplierStatIDs", "type": "*composed", "value": "~11"},
+					{"tag": "SupplierWeight", "field_id": "SupplierWeight", "type": "*composed", "value": "~12"},
+					{"tag": "SupplierBlocker", "field_id": "SupplierBlocker", "type": "*composed", "value": "~13"},
+					{"tag": "SupplierParameters", "field_id": "SupplierParameters", "type": "*composed", "value": "~14"},
+					{"tag": "Weight", "field_id": "Weight", "type": "*composed", "value": "~15"},
+				],
+			},
+		],
+	},
+	{
+		"id": "FilterLoader",									// identifier of the Loader
+		"enabled": false,									// starts as service: <true|false>.
+		"dry_run": false,									// do not send the CDRs to CDRS, just parse them
+		"run_delay": 0,										// sleep interval in seconds between consecutive runs, 0 to use automation via inotify
+		"lock_filename": ".cgr.lock",						// Filename containing concurrency lock in case of delayed processing
+		"caches_conns": [
+			{"address": "*internal"},						// address where to reach the CacheS for data reload, empty for no reloads  <""|*internal|x.y.z.y:1234>
+		],
+		"field_separator": ",",								// separator used in case of csv files
+		"tp_in_dir": "/tmp/FilterIn",		// absolute path towards the directory where the CDRs are stored
+		"tp_out_dir": "/tmp/FilterOut",	// absolute path towards the directory where processed CDRs will be moved
+		"data":[	
+			{
+				"type": "*filters",						// data source type
+				"file_name": "Filters.csv",				// file name in the tp_in_dir
+				"fields": [
+					{"tag": "Tenant", "field_id": "Tenant", "type": "*composed", "value": "~0", "mandatory": true},
+					{"tag": "ID", "field_id": "ID", "type": "*composed", "value": "~1", "mandatory": true},
+					{"tag": "FilterType", "field_id": "FilterType", "type": "*composed", "value": "~2"},
+					{"tag": "FilterFieldName", "field_id": "FilterFieldName", "type": "*composed", "value": "~3"},
+					{"tag": "FilterFieldValues", "field_id": "FilterFieldValues", "type": "*composed", "value": "~4"},
+					{"tag": "ActivationInterval", "field_id": "ActivationInterval", "type": "*composed", "value": "~5"},
+				],
+			},	
+		],
+	},
+],
+
+
+
+"attributes": {
+	"enabled": true,
+},
+
+
+"chargers": {
+	"enabled": true,
+	"attributes_conns": [
+		{"address": "*internal"},
+	],
+},
+
+
+"resources": {
+	"enabled": true,
+	"store_interval": "1s",
+	"thresholds_conns": [
+		{"address": "*internal"}
+	],
+},
+
+
+"stats": {
+	"enabled": true,
+	"store_interval": "1s",
+	"thresholds_conns": [
+		{"address": "*internal"}
+	],
+},
+
+"thresholds": {
+	"enabled": true,
+	"store_interval": "1s",
+},
+
+
+"suppliers": {
+	"enabled": true,
+	"prefix_indexed_fields":["Destination",],
+	"stats_conns": [
+		{"address": "*internal"},
+	],
+},
+
+
+"sessions": {
+	"enabled": true,
+	"suppliers_conns": [
+		{"address": "*internal"}
+	],
+	"resources_conns": [
+		{"address": "*internal"}
+	],
+	"attributes_conns": [
+		{"address": "*internal"}
+	],
+	"rals_conns": [
+		{"address": "*internal"}
+	],
+},
+
+
+"migrator":{
+	"out_stordb_password": "CGRateS.org",
+	"users_filters":["Account"],
+},
+
+
+}
diff --git a/general_tests/session_it_test.go b/general_tests/session_it_test.go
new file mode 100644
index 000000000..3a8e0d056
--- /dev/null
+++ b/general_tests/session_it_test.go
@@ -0,0 +1,191 @@
+// +build integration
+
+/*
+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 general_tests
+
+import (
+	"net/rpc"
+	"net/rpc/jsonrpc"
+	"path"
+	"testing"
+	"time"
+
+	"github.com/cgrates/cgrates/config"
+	"github.com/cgrates/cgrates/engine"
+	"github.com/cgrates/cgrates/sessions"
+	"github.com/cgrates/cgrates/utils"
+)
+
+var (
+	sesCfgPath string
+	sesCfg     *config.CGRConfig
+	sesRPC     *rpc.Client
+	sesAccount = "refundAcc"
+	sesTenant  = "cgrates.org"
+)
+
+// test for 0 balance with session terminate with 1s usage
+func TestSesItLoadConfig(t *testing.T) {
+	sesCfgPath = path.Join(*dataDir, "conf", "samples", "tutmysql_internal")
+	if sesCfg, err = config.NewCGRConfigFromFolder(sesCfgPath); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestSesItResetDataDB(t *testing.T) {
+	if err := engine.InitDataDb(sesCfg); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestSesItResetStorDb(t *testing.T) {
+	if err := engine.InitStorDb(sesCfg); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestSesItStartEngine(t *testing.T) {
+	if _, err := engine.StopStartEngine(sesCfgPath, *waitRater); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestSesItRPCConn(t *testing.T) {
+	var err error
+	sesRPC, err = jsonrpc.Dial("tcp", sesCfg.ListenCfg().RPCJSONListen)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestSesItLoadFromFolder(t *testing.T) {
+	var reply string
+	attrs := &utils.AttrLoadTpFromFolder{FolderPath: path.Join(*dataDir, "tariffplans", "testit")}
+	if err := sesRPC.Call("ApierV1.LoadTariffPlanFromFolder", attrs, &reply); err != nil {
+		t.Error(err)
+	}
+	time.Sleep(500 * time.Millisecond)
+}
+
+func testAccountBalance2(t *testing.T, sracc, srten, balType string, expected float64) {
+	var acnt *engine.Account
+	attrs := &utils.AttrGetAccount{
+		Tenant:  srten,
+		Account: sracc,
+	}
+	if err := sesRPC.Call("ApierV2.GetAccount", attrs, &acnt); err != nil {
+		t.Error(err)
+	} else if rply := acnt.BalanceMap[balType].GetTotalValue(); rply != expected {
+		t.Errorf("Expecting: %v, received: %v",
+			expected, rply)
+	}
+}
+
+func TestSesItAddVoiceBalance(t *testing.T) {
+	attrSetBalance := utils.AttrSetBalance{
+		Tenant:        sesTenant,
+		Account:       sesAccount,
+		BalanceType:   utils.MONETARY,
+		BalanceID:     utils.StringPointer("TestDynamicDebitBalance"),
+		Value:         utils.Float64Pointer(0),
+		RatingSubject: utils.StringPointer("*zero1s"),
+	}
+	var reply string
+	if err := sesRPC.Call("ApierV2.SetBalance", attrSetBalance, &reply); err != nil {
+		t.Error(err)
+	} else if reply != utils.OK {
+		t.Errorf("Received: %s", reply)
+	}
+	t.Run("TestAddVoiceBalance", func(t *testing.T) { testAccountBalance2(t, sesAccount, sesTenant, utils.MONETARY, 0) })
+}
+
+func TestSesItInitSession(t *testing.T) {
+	args1 := &sessions.V1InitSessionArgs{
+		InitSession: true,
+		CGREvent: utils.CGREvent{
+			Tenant: sesTenant,
+			ID:     "TestSesItInitiateSession",
+			Event: map[string]interface{}{
+				utils.Tenant:      sesTenant,
+				utils.Category:    "call",
+				utils.ToR:         utils.VOICE,
+				utils.OriginID:    "TestRefund",
+				utils.RequestType: utils.META_PREPAID,
+				utils.Account:     sesAccount,
+				utils.Subject:     "TEST",
+				utils.Destination: "TEST",
+				utils.SetupTime:   time.Date(2018, time.January, 7, 16, 60, 0, 0, time.UTC),
+				utils.AnswerTime:  time.Date(2018, time.January, 7, 16, 60, 10, 0, time.UTC),
+				utils.Usage:       5 * time.Second,
+			},
+		},
+	}
+	var rply1 sessions.V1InitSessionReply
+	if err := sesRPC.Call(utils.SessionSv1InitiateSession,
+		args1, &rply1); err != nil {
+		t.Error(err)
+		return
+	} else if *rply1.MaxUsage != 0 {
+		t.Errorf("Unexpected MaxUsage: %v", rply1.MaxUsage)
+	}
+	t.Run("TestInitSession", func(t *testing.T) { testAccountBalance2(t, sesAccount, sesTenant, utils.MONETARY, 0) })
+}
+
+func TestSesItTerminateSession(t *testing.T) {
+	args := &sessions.V1TerminateSessionArgs{
+		TerminateSession: true,
+		CGREvent: utils.CGREvent{
+			Tenant: sesTenant,
+			ID:     "TestSesItUpdateSession",
+			Event: map[string]interface{}{
+				utils.Tenant:      sesTenant,
+				utils.Category:    "call",
+				utils.ToR:         utils.VOICE,
+				utils.OriginID:    "TestRefund",
+				utils.RequestType: utils.META_PREPAID,
+				utils.Account:     sesAccount,
+				utils.Subject:     "TEST",
+				utils.Destination: "TEST",
+				utils.SetupTime:   time.Date(2018, time.January, 7, 16, 60, 0, 0, time.UTC),
+				utils.AnswerTime:  time.Date(2018, time.January, 7, 16, 60, 10, 0, time.UTC),
+				utils.Usage:       1 * time.Second,
+			},
+		},
+	}
+	var rply string
+	if err := sesRPC.Call(utils.SessionSv1TerminateSession,
+		args, &rply); err != nil {
+		t.Error(err)
+	}
+	if rply != utils.OK {
+		t.Errorf("Unexpected reply: %s", rply)
+	}
+	aSessions := make([]*sessions.ActiveSession, 0)
+	if err := sesRPC.Call(utils.SessionSv1GetActiveSessions, nil, &aSessions); err == nil ||
+		err.Error() != utils.ErrNotFound.Error() {
+		t.Error(err)
+	}
+	t.Run("TestTerminateSession", func(t *testing.T) { testAccountBalance2(t, sesAccount, sesTenant, utils.MONETARY, 0) })
+}
+
+func TestSesItStopCgrEngine(t *testing.T) {
+	if err := engine.KillEngine(100); err != nil {
+		t.Error(err)
+	}
+}
diff --git a/sessions/sessions.go b/sessions/sessions.go
index bf96e1391..5f538fdd8 100644
--- a/sessions/sessions.go
+++ b/sessions/sessions.go
@@ -485,7 +485,9 @@ func (sS *SessionS) debitSession(s *Session, sRunIdx int, dur time.Duration,
 	ec := engine.NewEventCostFromCallCost(cc, s.CGRID,
 		sr.Event.GetStringIgnoreErrors(utils.RunID))
 	if sr.EventCost == nil {
-		sr.EventCost = ec
+		if ccDuration != time.Duration(0) {
+			sr.EventCost = ec
+		}
 	} else {
 		sr.EventCost.Merge(ec)
 	}