diff --git a/engine/account.go b/engine/account.go
index 4b01a213e..5d2e6dac9 100644
--- a/engine/account.go
+++ b/engine/account.go
@@ -208,7 +208,7 @@ func (account *Account) getAlldBalancesForPrefix(destination, category, balanceT
 	return
 }
 
-func (ub *Account) debitCreditBalance(cd *CallDescriptor, count bool, dryRun bool) (cc *CallCost, err error) {
+func (ub *Account) debitCreditBalance(cd *CallDescriptor, count bool, dryRun bool, goNegative bool) (cc *CallCost, err error) {
 	usefulUnitBalances := ub.getAlldBalancesForPrefix(cd.Destination, cd.Category, cd.TOR+cd.Direction)
 	usefulMoneyBalances := ub.getAlldBalancesForPrefix(cd.Destination, cd.Category, CREDIT+cd.Direction)
 	//log.Print(usefulMoneyBalances, usefulUnitBalances)
@@ -240,7 +240,7 @@ func (ub *Account) debitCreditBalance(cd *CallDescriptor, count bool, dryRun boo
 						ub.DebitConnectionFee(cc, usefulMoneyBalances, count)
 					}
 					// for i, ts := range cc.Timespans {
-					//	log.Printf("cc.times[an[%d]: %+v\n", i, ts)
+					//  log.Printf("cc.times[an[%d]: %+v\n", i, ts)
 					// }
 					cd.TimeStart = cc.GetEndTime()
 					//log.Printf("CD: %+v", cd)
@@ -302,25 +302,27 @@ func (ub *Account) debitCreditBalance(cd *CallDescriptor, count bool, dryRun boo
 		// this is the first add, debit the connect fee
 		ub.DebitConnectionFee(cc, usefulMoneyBalances, count)
 	}
-	//log.Printf("Left CC: %+v", leftCC)
-	// get the default money balanance
-	// and go negative on it with the amount still unpaid
-	for _, ts := range leftCC.Timespans {
-		if ts.Increments == nil {
-			ts.createIncrementsSlice()
+	if leftCC.Cost == 0 || goNegative {
+		//log.Printf("Left CC: %+v", leftCC)
+		// get the default money balanance
+		// and go negative on it with the amount still unpaid
+		if len(leftCC.Timespans) > 0 && leftCC.Cost > 0 && !ub.AllowNegative {
+			err = errors.New("not enough credit")
 		}
-		for _, increment := range ts.Increments {
-			cost := increment.Cost
-			defaultBalance := ub.GetDefaultMoneyBalance(leftCC.Direction)
-			defaultBalance.SubstractAmount(cost)
-			increment.BalanceInfo.MoneyBalanceUuid = defaultBalance.Uuid
-			increment.BalanceInfo.AccountId = ub.Id
-			increment.paid = true
-			if count {
-				ub.countUnits(&Action{BalanceType: CREDIT, Direction: leftCC.Direction, Balance: &Balance{Value: cost, DestinationId: leftCC.Destination}})
+		for _, ts := range leftCC.Timespans {
+			if ts.Increments == nil {
+				ts.createIncrementsSlice()
 			}
-			if !ub.AllowNegative {
-				err = errors.New("not enough credit")
+			for _, increment := range ts.Increments {
+				cost := increment.Cost
+				defaultBalance := ub.GetDefaultMoneyBalance(leftCC.Direction)
+				defaultBalance.SubstractAmount(cost)
+				increment.BalanceInfo.MoneyBalanceUuid = defaultBalance.Uuid
+				increment.BalanceInfo.AccountId = ub.Id
+				increment.paid = true
+				if count {
+					ub.countUnits(&Action{BalanceType: CREDIT, Direction: leftCC.Direction, Balance: &Balance{Value: cost, DestinationId: leftCC.Destination}})
+				}
 			}
 		}
 	}
diff --git a/engine/account_test.go b/engine/account_test.go
index a8809d8bb..c5f392239 100644
--- a/engine/account_test.go
+++ b/engine/account_test.go
@@ -185,7 +185,7 @@ func TestDebitCreditZeroSecond(t *testing.T) {
 	}
 	rifsBalance := &Account{Id: "other", BalanceMap: map[string]BalanceChain{MINUTES + OUTBOUND: BalanceChain{b1}, CREDIT + OUTBOUND: BalanceChain{&Balance{Category: "0", Value: 21}}}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -228,7 +228,7 @@ func TestDebitCreditZeroMinute(t *testing.T) {
 		CREDIT + OUTBOUND:  BalanceChain{&Balance{Value: 21}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -275,7 +275,7 @@ func TestDebitCreditZeroMixedMinute(t *testing.T) {
 		CREDIT + OUTBOUND:  BalanceChain{&Balance{Value: 21}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -326,7 +326,7 @@ func TestDebitCreditNoCredit(t *testing.T) {
 		MINUTES + OUTBOUND: BalanceChain{b1},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err == nil {
 		t.Error("Showing no enough credit error ")
 	}
@@ -378,7 +378,7 @@ func TestDebitCreditHasCredit(t *testing.T) {
 		CREDIT + OUTBOUND:  BalanceChain{&Balance{Uuid: "moneya", Value: 110}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -426,7 +426,7 @@ func TestDebitCreditSplitMinutesMoney(t *testing.T) {
 		CREDIT + OUTBOUND:  BalanceChain{&Balance{Uuid: "moneya", Value: 50}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -478,7 +478,7 @@ func TestDebitCreditMoreTimespans(t *testing.T) {
 		MINUTES + OUTBOUND: BalanceChain{b1},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -527,7 +527,7 @@ func TestDebitCreditMoreTimespansMixed(t *testing.T) {
 		MINUTES + OUTBOUND: BalanceChain{b1, b2},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -577,7 +577,7 @@ func TestDebitCreditNoConectFeeCredit(t *testing.T) {
 		MINUTES + OUTBOUND: BalanceChain{b1},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err == nil {
 		t.Error("Error showing debiting balance error: ", err)
 	}
@@ -621,7 +621,7 @@ func TestDebitCreditMoneyOnly(t *testing.T) {
 		CREDIT + OUTBOUND: BalanceChain{&Balance{Uuid: "money", Value: 50}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err == nil {
 		t.Error("Missing noy enough credit error ")
 	}
@@ -675,7 +675,7 @@ func TestDebitCreditSubjectMinutes(t *testing.T) {
 		CREDIT + OUTBOUND:  BalanceChain{&Balance{Uuid: "moneya", Value: 350}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -729,7 +729,7 @@ func TestDebitCreditSubjectMoney(t *testing.T) {
 		CREDIT + OUTBOUND: BalanceChain{&Balance{Uuid: "moneya", Value: 75, DestinationId: "NAT", RatingSubject: "minu"}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -780,7 +780,7 @@ func TestDebitCreditSubjectMoney(t *testing.T) {
 		CREDIT + OUTBOUND:  BalanceChain{&Balance{Uuid: "moneya", Value: 19500, RatingSubject: "minu"}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -842,7 +842,7 @@ func TestDebitCreditSubjectMixedMoreTS(t *testing.T) {
 		CREDIT + OUTBOUND:  BalanceChain{&Balance{Uuid: "moneya", Value: 50, RatingSubject: "minu"}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err == nil {
 		t.Error("Error showing debiting balance error: ", err)
 	}
@@ -906,7 +906,7 @@ func TestDebitCreditSubjectMixedPartPay(t *testing.T) {
 		CREDIT + OUTBOUND:  BalanceChain{&Balance{Uuid: "moneya", Value: 75, RatingSubject: "minu"}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err == nil {
 		t.Error("Error showing debiting balance error: ", err)
 	}
@@ -1173,7 +1173,7 @@ func TestDebitShared(t *testing.T) {
 	accountingStorage.SetAccount(groupie)
 	accountingStorage.SetSharedGroup(sg)
 	cache2go.Cache(SHARED_GROUP_PREFIX+"SG_TEST", sg)
-	cc, err := rif.debitCreditBalance(cd, false, false)
+	cc, err := rif.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -1233,7 +1233,7 @@ func TestDebitSMS(t *testing.T) {
 		CREDIT + OUTBOUND: BalanceChain{&Balance{Value: 21}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -1283,7 +1283,7 @@ func TestDebitDataUnits(t *testing.T) {
 		CREDIT + OUTBOUND: BalanceChain{&Balance{Value: 21}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
@@ -1332,7 +1332,7 @@ func TestDebitDataMoney(t *testing.T) {
 		CREDIT + OUTBOUND: BalanceChain{&Balance{Value: 160}},
 	}}
 	var err error
-	cc, err = rifsBalance.debitCreditBalance(cd, false, false)
+	cc, err = rifsBalance.debitCreditBalance(cd, false, false, true)
 	if err != nil {
 		t.Error("Error debiting balance: ", err)
 	}
diff --git a/engine/calldesc.go b/engine/calldesc.go
index f0db7f388..2c2e8fd2c 100644
--- a/engine/calldesc.go
+++ b/engine/calldesc.go
@@ -464,7 +464,7 @@ func (origCD *CallDescriptor) getMaxSessionDuration(origAcc *Account) (time.Dura
 	}
 	cd := origCD.Clone()
 	initialDuration := cd.TimeEnd.Sub(cd.TimeStart)
-	cc, _ := cd.debit(account, true)
+	cc, _ := cd.debit(account, true, false)
 
 	//log.Printf("CC: %+v", cc)
 
@@ -526,7 +526,7 @@ func (cd *CallDescriptor) GetMaxSessionDuration() (duration time.Duration, err e
 
 // Interface method used to add/substract an amount of cents or bonus seconds (as returned by GetCost method)
 // from user's money balance.
-func (cd *CallDescriptor) debit(account *Account, dryRun bool) (cc *CallCost, err error) {
+func (cd *CallDescriptor) debit(account *Account, dryRun bool, goNegative bool) (cc *CallCost, err error) {
 	if !dryRun {
 		defer accountingStorage.SetAccount(account)
 	}
@@ -534,7 +534,7 @@ func (cd *CallDescriptor) debit(account *Account, dryRun bool) (cc *CallCost, er
 		cd.TOR = MINUTES
 	}
 	//log.Printf("Debit CD: %+v", cd)
-	cc, err = account.debitCreditBalance(cd, !dryRun, dryRun)
+	cc, err = account.debitCreditBalance(cd, !dryRun, dryRun, goNegative)
 	//log.Print("HERE: ", cc, err)
 	if err != nil {
 		Logger.Err(fmt.Sprintf("<Rater> Error getting cost for account key %v: %v", cd.GetAccountKey(), err))
@@ -563,7 +563,7 @@ func (cd *CallDescriptor) Debit() (cc *CallCost, err error) {
 	} else {
 		if memberIds, err := account.GetUniqueSharedGroupMembers(cd.Destination, cd.Direction, cd.Category, cd.TOR); err == nil {
 			AccLock.GuardMany(memberIds, func() (float64, error) {
-				cc, err = cd.debit(account, false)
+				cc, err = cd.debit(account, false, true)
 				return 0, err
 			})
 		} else {
@@ -597,7 +597,7 @@ func (cd *CallDescriptor) MaxDebit() (cc *CallCost, err error) {
 					cd.TimeEnd = cd.TimeStart.Add(remainingDuration)
 					cd.DurationIndex -= initialDuration - remainingDuration
 				}
-				cc, err = cd.debit(account, false)
+				cc, err = cd.debit(account, false, true)
 				//log.Print(balanceMap[0].Value, balanceMap[1].Value)
 				return 0, err
 			})
diff --git a/engine/calldesc_test.go b/engine/calldesc_test.go
index 1210e3cc5..ffcf050ab 100644
--- a/engine/calldesc_test.go
+++ b/engine/calldesc_test.go
@@ -523,7 +523,10 @@ func TestMaxSessionModifiesCallDesc(t *testing.T) {
 		TOR:           MINUTES,
 	}
 	initial := cd.Clone()
-	cd.GetMaxSessionDuration()
+	_, err := cd.GetMaxSessionDuration()
+	if err != nil {
+		t.Error("Got error from max duration: ", err)
+	}
 	cd.account = nil // it's OK to cache the account
 	if !reflect.DeepEqual(cd, initial) {
 		t.Errorf("GetMaxSessionDuration is changing the call descriptor %+v != %+v", cd, initial)
@@ -542,7 +545,10 @@ func TestMaxDebitDurationNoGreatherThanInitialDuration(t *testing.T) {
 		Destination: "0723",
 	}
 	initialDuration := cd.TimeEnd.Sub(cd.TimeStart)
-	result, _ := cd.GetMaxSessionDuration()
+	result, err := cd.GetMaxSessionDuration()
+	if err != nil {
+		t.Error("Got error from max duration: ", err)
+	}
 	if result > initialDuration {
 		t.Error("max session duration greather than initial duration", initialDuration, result)
 	}