diff --git a/timeslots/interval_test.go b/timespans/interval_test.go
similarity index 100%
rename from timeslots/interval_test.go
rename to timespans/interval_test.go
diff --git a/timeslots/intervals.go b/timespans/intervals.go
similarity index 93%
rename from timeslots/intervals.go
rename to timespans/intervals.go
index 2e11696fc..0799231e9 100644
--- a/timeslots/intervals.go
+++ b/timespans/intervals.go
@@ -113,7 +113,10 @@ func (i *Interval) getLeftMargin(t time.Time) (rigthtTime time.Time){
 }
 
 /*
-
+Splits the given timespan according to how it relates to the interval.
+It will modify the endtime of the received timespan and it will return
+a new timespan starting from the end of the received one.
+The interval will attach itself to the timespan that overlaps the interval.
 */
 func (i *Interval) Split(ts *TimeSpan) (nts *TimeSpan) {
 	// if the span is not in interval return nil
diff --git a/timeslots/kyoto_storage.go b/timespans/kyoto_storage.go
similarity index 100%
rename from timeslots/kyoto_storage.go
rename to timespans/kyoto_storage.go
diff --git a/timeslots/redis_storage.go b/timespans/redis_storage.go
similarity index 100%
rename from timeslots/redis_storage.go
rename to timespans/redis_storage.go
diff --git a/timeslots/storage_interface.go b/timespans/storage_interface.go
similarity index 100%
rename from timeslots/storage_interface.go
rename to timespans/storage_interface.go
diff --git a/timeslots/timeslots.go b/timespans/timeslots.go
similarity index 77%
rename from timeslots/timeslots.go
rename to timespans/timeslots.go
index bd46b1fa4..58a30c97e 100644
--- a/timeslots/timeslots.go
+++ b/timespans/timeslots.go
@@ -7,6 +7,50 @@ import (
 	"encoding/json"
 )
 
+/*
+A unit in which a call will be split that has a specific price related interval attached to it.
+*/
+type TimeSpan struct {
+	TimeStart, TimeEnd time.Time
+	Interval *Interval
+}
+
+/*
+Returns the duration of the timespan
+*/
+func (ts *TimeSpan) GetDuration() time.Duration {
+	return ts.TimeEnd.Sub(ts.TimeStart)
+}
+
+/*
+Returns the cost of the timespan according to the relevant cost interval.
+If the first parameter is true then it adds the connection fee to the cost.
+*/
+func (ts *TimeSpan) GetCost(first bool) return (cost float32) {
+	if ts.Interval.BillingUnit > 0 {
+		cost = (ts.GetDuration().seconds() / ts.Interval.BillingUnit) * ts.Interval.Price
+	} else {
+		cost = ts.GetDuration().seconds() * ts.Interval.Price
+	}
+	if first {
+		cost += ts.Interval.ConnectFee
+	}
+	return
+}
+
+/*
+will set ne interval as spans's interval if new ponder is greater then span's interval ponder
+or if the ponders are equal and new price is lower then spans's interval price
+*/
+func (ts *TimeSpan) SetInterval(i *Interval) {
+	if ts.Interval == nil || ts.Interval.Ponder < i.Ponder {
+		ts.Interval = i
+	}
+	if ts.Interval.Ponder == i.Ponder && i.Price < ts.Interval.Price {
+		ts.Interval = i
+	}
+}
+
 /*
 A structure containing the time intervals with the cost information and the 
 ActivationTime when those intervals will be applied.
@@ -23,14 +67,12 @@ func (c *ActivationPeriod) AddInterval(is ...*Interval) {
 }
 
 /*
-A structure that contains the data extracted from the storage.
-The CstmId and the Destination prefix represent the key and the 
-ActivationPeriods slice is the value.
+The input stucture that contains call information.
 */
-type Customer struct {
-	CstmId string
-	Subject string
-	DestinationPrefix string
+type CallDescription struct {
+	TOR int
+	CstmId, Subject, Destination string
+	TimeStart, TimeEnd time.Time
 	ActivationPeriods []*ActivationPeriod
 }
 
@@ -63,41 +105,12 @@ func (c *Customer) decodeValue(v []byte) {
 }
 
 /*
-A unit in which a call will be split that has a specific price related interval attached to it.
 */
-type TimeSpan struct {
-	TimeStart, TimeEnd time.Time
-	Interval *Interval
+func (cd *CallDescription) GetCost() (result *CallCost) {
+	ts := &TimeSpan{TimeStart: cd.TimeStart, TimeEnd: cd.TimeEnd}
+	c := &Customer{CstmId:, Subject:, DestinationPrefix: }
 }
 
-/*
-Returns the duration of the timespan
-*/
-func (ts *TimeSpan) GetDuration() time.Duration {
-	return ts.TimeEnd.Sub(ts.TimeStart)
-}
-
-/*
-will set ne interval as spans's interval if new ponder is greater then span's interval ponder
-or if the ponders are equal and new price is lower then spans's interval price
-*/
-func (ts *TimeSpan) SetInterval(i *Interval) {
-	if ts.Interval == nil || ts.Interval.Ponder < i.Ponder {
-		ts.Interval = i
-	}
-	if ts.Interval.Ponder == i.Ponder && i.Price < ts.Interval.Price {
-		ts.Interval = i
-	}
-}
-
-/*
-The input stucture that contains call information.
-*/
-type CallDescription struct {
-	TOR int
-	CstmId, Subject, Destination string
-	TimeStart, TimeEnd time.Time
-}
 
 
 /*
@@ -110,7 +123,4 @@ type CallCost struct {
 //	ratesInfo *RatingProfile
 }
 
-func GetCost(in *CallDescription, sg StorageGetter) (result *CallCost, err error) {
-	return &CallCost{TOR: 1, CstmId:"",Subject:"", Prefix:"", Cost:1, ConnectFee:1}, nil
-}
 
diff --git a/timeslots/timeslots_test.go b/timespans/timeslots_test.go
similarity index 100%
rename from timeslots/timeslots_test.go
rename to timespans/timeslots_test.go