diff --git a/app/models/ticket.rb b/app/models/ticket.rb
index 0e3e2e6b7..3b2ef0182 100644
--- a/app/models/ticket.rb
+++ b/app/models/ticket.rb
@@ -557,10 +557,6 @@ class Ticket < ApplicationModel
       end
     }
 
-    # get and set calendar settings
-    if sla_selected
-      TimeCalculation.config( sla_selected.data, sla_selected.timezone, time )
-    end
     return sla_selected
   end
 
@@ -609,13 +605,13 @@ class Ticket < ApplicationModel
 
     # first response
     if sla_selected.first_response_time
-      self.first_response_escal_date = TimeCalculation.dest_time( created_at, sla_selected.first_response_time )
+      self.first_response_escal_date = TimeCalculation.dest_time( created_at, sla_selected.first_response_time, sla_selected.data, sla_selected.timezone )
 
       # set ticket escalation
       self.escalation_time = self._escalation_calculation_higher_time( self.escalation_time, self.first_response_escal_date, self.first_response )
     end
     if self.first_response# && !self.first_response_in_min
-      self.first_response_in_min = TimeCalculation.business_time_diff( self.created_at, self.first_response )
+      self.first_response_in_min = TimeCalculation.business_time_diff( self.created_at, self.first_response, sla_selected.data, sla_selected.timezone  )
     end
     # set sla time
     if sla_selected.first_response_time && self.first_response_in_min
@@ -629,13 +625,13 @@ class Ticket < ApplicationModel
       last_update = self.created_at
     end
     if sla_selected.update_time
-      self.update_time_escal_date = TimeCalculation.dest_time( last_update, sla_selected.update_time )
+      self.update_time_escal_date = TimeCalculation.dest_time( last_update, sla_selected.update_time, sla_selected.data, sla_selected.timezone  )
 
       # set ticket escalation
       self.escalation_time = self._escalation_calculation_higher_time( self.escalation_time, self.update_time_escal_date, false )
     end
     if self.last_contact_agent
-      self.update_time_in_min = TimeCalculation.business_time_diff( self.created_at, self.last_contact_agent )
+      self.update_time_in_min = TimeCalculation.business_time_diff( self.created_at, self.last_contact_agent, sla_selected.data, sla_selected.timezone  )
     end
 
     # set sla time
@@ -646,13 +642,13 @@ class Ticket < ApplicationModel
 
     # close time
     if sla_selected.close_time
-      self.close_time_escal_date = TimeCalculation.dest_time( self.created_at, sla_selected.close_time )
+      self.close_time_escal_date = TimeCalculation.dest_time( self.created_at, sla_selected.close_time, sla_selected.data, sla_selected.timezone  )
 
       # set ticket escalation
       self.escalation_time = self._escalation_calculation_higher_time( self.escalation_time, self.close_time_escal_date, self.close_time )
     end
     if self.close_time# && !self.close_time_in_min
-      self.close_time_in_min = TimeCalculation.business_time_diff( self.created_at, self.close_time )
+      self.close_time_in_min = TimeCalculation.business_time_diff( self.created_at, self.close_time, sla_selected.data, sla_selected.timezone  )
     end
     # set sla time
     if sla_selected.close_time && self.close_time_in_min
diff --git a/lib/business_time/business_minutes.rb b/lib/business_time/business_minutes.rb
deleted file mode 100644
index b37527d3f..000000000
--- a/lib/business_time/business_minutes.rb
+++ /dev/null
@@ -1,99 +0,0 @@
-module BusinessTime
-
-  class BusinessMinutes
-    def initialize(minutes)
-      @minutes = minutes
-    end
-
-    def ago
-      Time.zone ? before(Time.zone.now) : before(Time.now)
-    end
-
-    def from_now
-      Time.zone ?  after(Time.zone.now) : after(Time.now)
-    end
-
-    def after(time)
-      after_time = Time.roll_forward(time)
-      # Step through the minutes, skipping over non-business minutes
-      days = @minutes / 60 / 24
-      hours = ( @minutes - ( days * 60 * 24 ) ) / 60
-      minutes =  @minutes - ( (days * 60 * 24 ) + (hours * 60) )
-      if @minutes > 60 * 12
-        
-      end
-
-      local_sec = @minutes * 60
-      loop = true
-      while (loop == true) do
-        a = after_time
-        if local_sec >= 60 * 60
-          after_time = after_time + 1.hour
-        else
-          after_time = after_time + 1.minute
-        end
-
-        # Ignore minutes before opening and after closing
-        if (after_time > Time.end_of_workday(after_time))
-          after_time = after_time + off_minutes
-          if local_sec < 60 * 60
-            after_time = after_time - 60
-          else
-            after_time = after_time - 60 * 60
-          end
-          next
-        end
-
-        # Ignore weekends and holidays
-        while !Time.workday?(after_time)
-          after_time = Time.beginning_of_workday(after_time + 1.day)
-          a = after_time
-        end
-        diff = after_time - a
-        local_sec = local_sec - diff
-
-        if local_sec <= 0
-          loop = false
-          next
-        end
-
-      end
-      after_time
-    end
-    alias_method :since, :after
-
-    def before(time)
-      before_time = Time.roll_forward(time)
-      # Step through the hours, skipping over non-business hours
-      @minutes.times do
-        before_time = before_time - 1.minute
-
-        # Ignore hours before opening and after closing
-        if (before_time < Time.beginning_of_workday(before_time))
-          before_time = before_time - off_minutes
-        end
-
-        # Ignore weekends and holidays
-        while !Time.workday?(before_time)
-          before_time = before_time - 1.day
-        end
-      end
-      before_time
-    end
-
-    private
-
-    def off_minutes
-      return @gap if @gap
-      if Time.zone
-        gap_end = Time.zone.parse(BusinessTime::Config.beginning_of_workday)
-        gap_begin = (Time.zone.parse(BusinessTime::Config.end_of_workday)-1.day)
-      else
-        gap_end = Time.parse(BusinessTime::Config.beginning_of_workday)
-        gap_begin = (Time.parse(BusinessTime::Config.end_of_workday) - 1.day)
-      end
-      @gap = gap_end - gap_begin
-    end
-  end
-
-end
diff --git a/lib/business_time/core_ext/fixnum_minute.rb b/lib/business_time/core_ext/fixnum_minute.rb
deleted file mode 100644
index af6a894de..000000000
--- a/lib/business_time/core_ext/fixnum_minute.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-# hook into fixnum so we can say things like:
-#  5.business_minutes.from_now
-#  4.business_minutes.before(some_date_time)
-class Fixnum
-  include BusinessTime
-  
-  def business_minutes
-    BusinessMinutes.new(self)
-  end
-  alias_method :business_minute, :business_minutes
-end
\ No newline at end of file
diff --git a/lib/business_time/core_ext/time_fix.rb b/lib/business_time/core_ext/time_fix.rb
deleted file mode 100644
index ce000b22b..000000000
--- a/lib/business_time/core_ext/time_fix.rb
+++ /dev/null
@@ -1,130 +0,0 @@
-# Add workday and weekday concepts to the Time class
-class Time
-  class << self
-
-    # Gives the time at the end of the workday, assuming that this time falls on a
-    # workday.
-    # Note: It pretends that this day is a workday whether or not it really is a
-    # workday.
-    def end_of_workday(day)
-      format = "%B %d %Y #{BusinessTime::Config.end_of_workday}"
-      Time.zone ? Time.zone.parse(day.strftime(format)) :
-          Time.parse(day.strftime(format))
-    end
-
-    # Gives the time at the beginning of the workday, assuming that this time
-    # falls on a workday.
-    # Note: It pretends that this day is a workday whether or not it really is a
-    # workday.
-    def beginning_of_workday(day)
-      format = "%B %d %Y #{BusinessTime::Config.beginning_of_workday}"
-      Time.zone ? Time.zone.parse(day.strftime(format)) :
-          Time.parse(day.strftime(format))
-    end
-
-    # True if this time is on a workday (between 00:00:00 and 23:59:59), even if
-    # this time falls outside of normal business hours.
-    def workday?(day)
-      Time.weekday?(day) &&
-          !BusinessTime::Config.holidays.include?(day.to_date)
-    end
-
-    # True if this time falls on a weekday.
-    def weekday?(day)
-      BusinessTime::Config.weekdays.include? day.wday
-    end
-
-    def before_business_hours?(time)
-      time < beginning_of_workday(time)
-    end
-
-    def after_business_hours?(time)
-      time > end_of_workday(time)
-    end
-
-    # Rolls forward to the next beginning_of_workday
-    # when the time is outside of business hours
-    def roll_forward(time)
-      if (Time.before_business_hours?(time) || !Time.workday?(time))
-        next_business_time = Time.beginning_of_workday(time)
-      elsif Time.after_business_hours?(time + 1)
-        next_business_time = Time.beginning_of_workday(time) + 1.day
-      else
-        next_business_time = time.clone
-      end
-
-      while !Time.workday?(next_business_time)
-        next_business_time += 1.day
-      end
-
-      next_business_time
-    end
-
-  end
-end
-
-class Time
-
-  def business_time_until(to_time)
-
-    # Make sure that we will calculate time from A to B "clockwise"
-    direction = 1
-    if self < to_time
-      time_a = self
-      time_b = to_time
-    else
-      time_a = to_time
-      time_b = self
-      direction = -1
-    end
-    
-    # Align both times to the closest business hours
-    time_a = Time::roll_forward(time_a)
-    time_b = Time::roll_forward(time_b)
-    
-    # If same date, then calculate difference straight forward
-#    if time_a.to_date == time_b.to_date
-#      result = time_b - time_a
-#      return result *= direction
-#    end
-    
-    # Both times are in different dates
-    result = Time.parse(time_a.strftime('%Y-%m-%d ') + BusinessTime::Config.end_of_workday) - time_a   # First day
-    result += time_b - Time.parse(time_b.strftime('%Y-%m-%d ') + BusinessTime::Config.beginning_of_workday) # Last day
-    
-    # All days in between
-#puts "--- #{time_a}-#{time_b} - #{direction}"
-
-#    duration_of_working_day = Time.parse(BusinessTime::Config.end_of_workday) - Time.parse(BusinessTime::Config.beginning_of_workday)
-#    result += (time_a.to_date.business_days_until(time_b.to_date) - 1) * duration_of_working_day
- 
-    result = 0
-
-    # All days in between
-    time_c = time_a
-    while time_c.to_i < time_b.to_i do
-      end_of_workday = Time.end_of_workday(time_c)
-      if !Time.workday?(time_c)
-        time_c = Time.beginning_of_workday(time_c) + 1.day
-#        puts 'VACATIONS! ' + time_c.to_s
-      end
-      if time_c.to_date == time_b.to_date
-        if end_of_workday < time_b
-          result += end_of_workday - time_c
-          break
-        else
-          result += time_b - time_c
-          break
-        end
-      else
-        result += end_of_workday - time_c
-        time_c = Time::roll_forward(end_of_workday)
-      end
-      result += 1 if end_of_workday.to_s =~ /23:59:59/
-    end
-
-    # Make sure that sign is correct
-    result *= direction
-  end
-
-end
\ No newline at end of file
diff --git a/lib/time_calculation.rb b/lib/time_calculation.rb
index 04daa2060..f3e4608fc 100644
--- a/lib/time_calculation.rb
+++ b/lib/time_calculation.rb
@@ -1,10 +1,5 @@
-require 'business_time'
-require 'business_time/business_minutes'
-require 'business_time/core_ext/fixnum_minute'
-require 'business_time/core_ext/time_fix'
-
 module TimeCalculation
-  def self.config(config, timezone, start_time)
+  def self.working_hours(start_time, config, timezone)
     time_diff = 0
     if timezone
       begin
@@ -15,50 +10,286 @@ module TimeCalculation
         puts e.backtrace
       end
     end
-    beginning_of_workday = Time.parse("1977-10-27 #{config['beginning_of_workday']}") + time_diff
-    if beginning_of_workday
-      config['beginning_of_workday'] = "#{beginning_of_workday.hour}:#{beginning_of_workday.min}"
-    end
-    end_of_workday = Time.parse("1977-10-27 #{config['end_of_workday']}") + time_diff
-    if end_of_workday
-      config['end_of_workday'] = "#{end_of_workday.hour}:#{end_of_workday.min}"
-    end
-    BusinessTime::Config.beginning_of_workday = config['beginning_of_workday']
-    BusinessTime::Config.end_of_workday       = config['end_of_workday']
-    days = []
-    ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'].each {|day|
-      if config[day]
-        days.push day.downcase.to_sym
+    beginning_of_workday = Time.parse("1977-10-27 #{config['beginning_of_workday']}")
+    end_of_workday       = Time.parse("1977-10-27 #{config['end_of_workday']}") - 3600
+    config_ok = false
+    working_hours = {}
+    [:Mon, :Tue, :Wed, :Thu, :Fri, :Sat, :Sun].each {|day|
+      working_hours[day] = []
+      if config[day.to_s] == true || config[day.to_s] == day.to_s
+        config_ok = true
+        (0..23).each {|hour|
+          time = Time.parse("1977-10-27 #{hour}:00:00")
+          if time >= beginning_of_workday && time <= end_of_workday
+            working_hours[day].push true
+          else
+            working_hours[day].push nil
+          end
+        }
       end
     }
-    BusinessTime::Config.work_week = days
-    holidays = []
-    if config['holidays']
-      config['holidays'].each {|holiday|
-        date = Date.parse( holiday )
-        holidays.push date.to_date
+
+    if !config_ok
+      raise "sla config is invalid! " + config.inspect
+    end
+
+    # shift working hours / if needed
+    if time_diff && time_diff != 0
+
+      hours_to_shift = (time_diff / 3600 ).round
+      move_items = {
+        :Mon => [],
+        :Tue => [],
+        :Wed => [],
+        :Thu => [],
+        :Fri => [],
+        :Sat => [],
+        :Sun => [],
+      }
+      (1..hours_to_shift).each {|count|
+        working_hours.each {|day, value|
+          if working_hours[day]
+            to_move = working_hours[day].shift
+            if day == :Mon
+              move_items[:Tue].push to_move
+            elsif day == :Tue
+              move_items[:Wed].push to_move
+            elsif day == :Wed
+              move_items[:Thu].push to_move
+            elsif day == :Thu
+              move_items[:Fri].push to_move
+            elsif day == :Fri
+              move_items[:Sat].push to_move
+            elsif day == :Sat
+              move_items[:Sun].push to_move
+            elsif day == :Sun
+              move_items[:Mon].push to_move
+            end
+          end
+        }
+      }
+      move_items.each {|day, value|
+        value.each {|item|
+          working_hours[day].push item
+        }
       }
     end
-    BusinessTime::Config.holidays = holidays
+    return working_hours
   end
 
-  def self.business_time_diff(start_time, end_time)
+  def self.business_time_diff(start_time, end_time, config, timezone = '')
     if start_time.class == String
       start_time  = Time.parse( start_time.to_s + 'UTC' )
     end
     if end_time.class == String
       end_time = Time.parse( end_time.to_s + 'UTC' )
     end
-    diff = start_time.business_time_until( end_time ) / 60
+
+    working_hours = self.working_hours(start_time, config, timezone)
+
+    week_day_map = {
+      1 => :Mon,
+      2 => :Tue,
+      3 => :Wed,
+      4 => :Thu,
+      5 => :Fri,
+      6 => :Sat,
+      0 => :Sun,
+    }
+
+    count = 0
+    calculation = true
+    first_loop  = true
+    while calculation do
+      week_day = start_time.wday
+      day      = start_time.day
+      month    = start_time.month
+      year     = start_time.year
+      hour     = start_time.hour
+
+
+      # check if it's vacation day
+      if config
+        if config['holidays']
+          if config['holidays'].include?("#{year}-#{month}-#{day}")
+
+            # jump to next day
+            start_time = start_time.beginning_of_day + 86400
+            next
+          end
+        end
+      end
+
+      # check if it's countable day
+      if working_hours[ week_day_map[week_day] ].empty?
+
+        # jump to next day
+        start_time = start_time.beginning_of_day + 86400
+        next
+      end
+
+      # fillup to first full hour
+      if first_loop
+        diff = end_time - start_time
+
+        if diff > 59 * 60
+            diff = start_time - start_time.beginning_of_hour
+        end
+        start_time += diff
+
+        # check if it's countable hour
+        if working_hours[ week_day_map[week_day] ][ hour ]
+          count += diff
+        end
+      end
+      first_loop = false
+
+      # loop to next hour
+      (hour..23).each { |next_hour|
+
+        # check if end time is lower
+        if start_time >= end_time
+          calculation = false
+          break
+        end
+
+        # check if end_time is within this hour
+        diff = end_time - start_time
+        if diff > 59 * 60
+          diff = 3600
+        end
+
+        # keep it in current day
+        if next_hour == 23
+          start_time += diff-1
+        else
+          start_time += diff
+        end
+
+        # check if it's business hour and count
+        if working_hours[ week_day_map[week_day] ][ next_hour ]
+          count += diff
+        end
+      }
+
+      # loop to next day
+      start_time = start_time.beginning_of_day + 86400
+    end
+
+    diff = count / 60
     diff.round
   end
 
-  def self.dest_time(start_time, diff_in_min)
+  def self.dest_time(start_time, diff_in_min, config, timezone = '')
     if start_time.class == String
       start_time = Time.parse( start_time.to_s + ' UTC' )
     end
-    dest_time = diff_in_min.round.business_minute.after( start_time )
-    return dest_time
+
+    # loop
+    working_hours = self.working_hours(start_time, config, timezone)
+
+    week_day_map = {
+      1 => :Mon,
+      2 => :Tue,
+      3 => :Wed,
+      4 => :Thu,
+      5 => :Fri,
+      6 => :Sat,
+      0 => :Sun,
+    }
+
+    count       = diff_in_min * 60
+    calculation = true
+    first_loop  = true
+    while calculation do
+      week_day = start_time.wday
+      day      = start_time.day
+      month    = start_time.month
+      year     = start_time.year
+      hour     = start_time.hour
+#puts "start outer loop #{start_time}-#{week_day}-#{year}-#{month}-#{day}-#{hour}|c#{count}"
+
+      # check if it's vacation day
+      if config
+        if config['holidays']
+          if config['holidays'].include?("#{year}-#{month}-#{day}")
+
+            # jump to next day
+            start_time = start_time.beginning_of_day + 86400
+            next
+          end
+        end
+      end
+
+      # check if it's countable day
+      if working_hours[ week_day_map[week_day] ].empty?
+
+        # jump to next day
+        start_time = start_time.beginning_of_day + 86400
+        next
+      end
+
+      # fillup to first full hour
+      if first_loop
+
+        # get rest of this hour
+        diff = 3600 - (start_time - start_time.beginning_of_hour)
+        start_time += diff
+
+        # check if it's countable hour
+        if working_hours[ week_day_map[week_day] ][ hour ]
+          count -= diff
+        end
+
+        # start on next hour of we moved to next
+        if diff != 0
+          hour += 1
+        end
+      end
+
+      first_loop = false
+
+      # loop to next hour
+      (hour..23).each { |next_hour|
+
+        diff = 3600
+
+        # check if count positiv
+        if count <= 0
+          calculation = false
+          break
+        end
+
+        # check if it's business hour and count
+        if working_hours[ week_day_map[week_day] ][ next_hour ]
+          # check if count is within this hour
+          if count > 59 * 60
+            diff = 3600
+          else
+            diff = count
+          end
+          count -= diff
+        end
+
+        # keep it in current day
+        if next_hour == 23
+          start_time += diff-1
+        else
+          start_time += diff
+        end
+      }
+
+      # check if count positiv
+      if count <= 0
+        calculation = false
+        break
+      end
+
+      # loop to next day
+      start_time = start_time.beginning_of_day + 86400
+    end
+
+    return start_time
   end
 
 end
diff --git a/test/unit/ticket_test.rb b/test/unit/ticket_test.rb
index 96672efb8..6f00d1d2f 100644
--- a/test/unit/ticket_test.rb
+++ b/test/unit/ticket_test.rb
@@ -455,7 +455,7 @@ class TicketTest < ActiveSupport::TestCase
     assert( ticket, "ticket created" )
     assert_equal( ticket.escalation_time, nil, 'ticket.escalation_time verify' )
 
-    # set sla's for timezone "Europe/Berlin" (+1), so UTC times are 8:00-17:00
+    # set sla's for timezone "Europe/Berlin" wintertime (+1), so UTC times are 8:00-17:00
     sla = Sla.create(
       :name => 'test sla 1',
       :condition => {},
@@ -473,17 +473,16 @@ class TicketTest < ActiveSupport::TestCase
       :created_by_id => 1,
     )
     ticket = Ticket.find(ticket.id)
-    assert_equal( ticket.escalation_time.gmtime.to_s, '2013-03-21 12:00:00 UTC', 'ticket.escalation_time verify 1' )
-    assert_equal( ticket.first_response_escal_date.gmtime.to_s, '2013-03-21 12:00:00 UTC', 'ticket.first_response_escal_date verify 1' )
-    assert_equal( ticket.update_time_escal_date.gmtime.to_s, '2013-03-21 13:00:00 UTC', 'ticket.update_time_escal_date verify 1' )
-    assert_equal( ticket.close_time_escal_date.gmtime.to_s, '2013-03-21 14:00:00 UTC', 'ticket.close_time_escal_date verify 1' )
+    assert_equal( ticket.escalation_time.gmtime.to_s, '2013-03-21 11:30:00 UTC', 'ticket.escalation_time verify 1' )
+    assert_equal( ticket.first_response_escal_date.gmtime.to_s, '2013-03-21 11:30:00 UTC', 'ticket.first_response_escal_date verify 1' )
+    assert_equal( ticket.update_time_escal_date.gmtime.to_s, '2013-03-21 12:30:00 UTC', 'ticket.update_time_escal_date verify 1' )
+    assert_equal( ticket.close_time_escal_date.gmtime.to_s, '2013-03-21 13:30:00 UTC', 'ticket.close_time_escal_date verify 1' )
 
     delete = sla.destroy
     assert( delete, "sla destroy" )
 
     delete = ticket.destroy
     assert( delete, "ticket destroy" )
-
     ticket = Ticket.create(
       :title           => 'some title äöüß',
       :group           => Group.lookup( :name => 'Users'),
@@ -498,7 +497,7 @@ class TicketTest < ActiveSupport::TestCase
     assert( ticket, "ticket created" )
     assert_equal( ticket.escalation_time, nil, 'ticket.escalation_time verify' )
 
-    # set sla's for timezone "Europe/Berlin" (+1), so UTC times are 8:00-17:00
+    # set sla's for timezone "Europe/Berlin" summertime (+2), so UTC times are 7:00-16:00
     sla = Sla.create(
       :name => 'test sla 1',
       :condition => {},
@@ -516,16 +515,60 @@ class TicketTest < ActiveSupport::TestCase
       :created_by_id => 1,
     )
     ticket = Ticket.find(ticket.id)
-    assert_equal( ticket.escalation_time.gmtime.to_s, '2013-10-21 13:00:00 UTC', 'ticket.escalation_time verify 1' )
-    assert_equal( ticket.first_response_escal_date.gmtime.to_s, '2013-10-21 13:00:00 UTC', 'ticket.first_response_escal_date verify 1' )
-    assert_equal( ticket.update_time_escal_date.gmtime.to_s, '2013-10-21 14:00:00 UTC', 'ticket.update_time_escal_date verify 1' )
-    assert_equal( ticket.close_time_escal_date.gmtime.to_s, '2013-10-21 15:00:00 UTC', 'ticket.close_time_escal_date verify 1' )
+    assert_equal( ticket.escalation_time.gmtime.to_s, '2013-10-21 11:30:00 UTC', 'ticket.escalation_time verify 1' )
+    assert_equal( ticket.first_response_escal_date.gmtime.to_s, '2013-10-21 11:30:00 UTC', 'ticket.first_response_escal_date verify 1' )
+    assert_equal( ticket.update_time_escal_date.gmtime.to_s, '2013-10-21 12:30:00 UTC', 'ticket.update_time_escal_date verify 1' )
+    assert_equal( ticket.close_time_escal_date.gmtime.to_s, '2013-10-21 13:30:00 UTC', 'ticket.close_time_escal_date verify 1' )
 
     delete = ticket.destroy
     assert( delete, "ticket destroy" )
 
     delete = sla.destroy
     assert( delete, "sla destroy" )
+
+    ticket = Ticket.create(
+      :title           => 'some title äöüß',
+      :group           => Group.lookup( :name => 'Users'),
+      :customer_id     => 2,
+      :ticket_state    => Ticket::State.lookup( :name => 'new' ),
+      :ticket_priority => Ticket::Priority.lookup( :name => '2 normal' ),
+      :created_at      => '2013-10-21 06:30:00 UTC',
+      :updated_at      => '2013-10-21 06:30:00 UTC',
+      :updated_by_id   => 1,
+      :created_by_id   => 1,
+    )
+    assert( ticket, "ticket created" )
+    assert_equal( ticket.escalation_time, nil, 'ticket.escalation_time verify' )
+
+    # set sla's for timezone "Europe/Berlin" summertime (+2), so UTC times are 7:00-16:00
+    sla = Sla.create(
+      :name => 'test sla 1',
+      :condition => {},
+      :data => {
+        "Mon"=>"Mon", "Tue"=>"Tue", "Wed"=>"Wed", "Thu"=>"Thu", "Fri"=>"Fri", "Sat"=>"Sat", "Sun"=>"Sun",
+        "beginning_of_workday" => "9:00",
+        "end_of_workday"       => "18:00",
+      },
+      :timezone            => 'Europe/Berlin',
+      :first_response_time => 120,
+      :update_time   => 180,
+      :close_time    => 240,
+      :active        => true,
+      :updated_by_id => 1,
+      :created_by_id => 1,
+    )
+    ticket = Ticket.find(ticket.id)
+    assert_equal( ticket.escalation_time.gmtime.to_s, '2013-10-21 09:00:00 UTC', 'ticket.escalation_time verify 1' )
+    assert_equal( ticket.first_response_escal_date.gmtime.to_s, '2013-10-21 09:00:00 UTC', 'ticket.first_response_escal_date verify 1' )
+    assert_equal( ticket.update_time_escal_date.gmtime.to_s, '2013-10-21 10:00:00 UTC', 'ticket.update_time_escal_date verify 1' )
+    assert_equal( ticket.close_time_escal_date.gmtime.to_s, '2013-10-21 11:00:00 UTC', 'ticket.close_time_escal_date verify 1' )
+
+    delete = sla.destroy
+    assert( delete, "sla destroy" )
+
+    delete = ticket.destroy
+    assert( delete, "ticket destroy" )
+
   end
 
 end
diff --git a/test/unit/working_time_test.rb b/test/unit/working_time_test.rb
index c03abc95e..4ea11697d 100644
--- a/test/unit/working_time_test.rb
+++ b/test/unit/working_time_test.rb
@@ -73,6 +73,8 @@ class WorkingTimeTest < ActiveSupport::TestCase
           ],
         },
       },
+
+      # test 5
       {
         :start  => '2013-02-28 17:00:00',
         :end    => '2013-02-28 23:59:59',
@@ -87,10 +89,158 @@ class WorkingTimeTest < ActiveSupport::TestCase
           'end_of_workday'       => '6:00 pm',
         },
       },
+
+      # test 6
+      {
+        :start  => '2013-02-28 17:00:00',
+        :end    => '2013-03-08 23:59:59',
+        :diff   => 3660,
+        :config => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 7
+      {
+        :start  => '2012-02-28 17:00:00',
+        :end    => '2013-03-08 23:59:59',
+        :diff   => 160860,
+        :config => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 8
+      {
+        :start  => '2013-02-28 17:01:00',
+        :end    => '2013-02-28 18:10:59',
+        :diff   => 61,
+        :config => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 9
+      {
+        :start  => '2013-02-28 18:01:00',
+        :end    => '2013-02-28 18:10:59',
+        :diff   => 0,
+        :config => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 10 / summertime
+      {
+        :start  => '2013-02-28 18:01:00',
+        :end    => '2013-02-28 18:10:59',
+        :diff   => 0,
+        :timezone => 'Europe/Berlin',
+        :config => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 11 / summertime
+      {
+        :start  => '2013-02-28 17:01:00',
+        :end    => '2013-02-28 17:10:59',
+        :diff   => 0,
+        :timezone => 'Europe/Berlin',
+        :config => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 12 / wintertime
+      {
+        :start  => '2013-08-29 17:01:00',
+        :end    => '2013-08-29 17:10:59',
+        :diff   => 0,
+        :timezone => 'Europe/Berlin',
+        :config => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 13 / summertime
+      {
+        :start  => '2013-02-28 16:01:00',
+        :end    => '2013-02-28 16:10:59',
+        :diff   => 10,
+        :timezone => 'Europe/Berlin',
+        :config => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 14 / wintertime
+      {
+        :start  => '2013-08-29 16:01:00',
+        :end    => '2013-08-29 16:10:59',
+        :diff   => 0,
+        :timezone => 'Europe/Berlin',
+        :config => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
     ]
     tests.each { |test|
-      TimeCalculation.config( test[:config], nil, test[:start] )
-      diff = TimeCalculation.business_time_diff( test[:start], test[:end] )
+      diff = TimeCalculation.business_time_diff( test[:start], test[:end], test[:config], test[:timezone] )
       assert_equal( diff, test[:diff], 'diff' )
     }
   end
@@ -178,6 +328,7 @@ class WorkingTimeTest < ActiveSupport::TestCase
         },
       },
 
+
       # test 6
       {
         :start     => '2012-12-17 08:00:00',
@@ -241,10 +392,112 @@ class WorkingTimeTest < ActiveSupport::TestCase
           'end_of_workday'       => '6:00 pm',
         },
       },
+
+      # test 11 / summertime
+      {
+        :start     => '2013-03-08 21:20:15',
+        :dest_time => '2013-03-11 09:00:00',
+        :diff      => 120,
+        :timezone  => 'Europe/Berlin',
+        :config    => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 12 / wintertime
+      {
+        :start     => '2013-09-06 21:20:15',
+        :dest_time => '2013-09-09 08:00:00',
+        :diff      => 120,
+        :timezone  => 'Europe/Berlin',
+        :config    => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '8:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 13 / wintertime
+      {
+        :start     => '2013-10-21 06:30:00',
+        :dest_time => '2013-10-21 09:00:00',
+        :diff      => 120,
+        :timezone  => 'Europe/Berlin',
+        :config    => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '9:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 14 / wintertime
+      {
+        :start     => '2013-10-21 04:34:15',
+        :dest_time => '2013-10-21 09:00:00',
+        :diff      => 120,
+        :timezone  => 'Europe/Berlin',
+        :config    => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '9:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 15 / wintertime
+      {
+        :start     => '2013-10-20 22:34:15',
+        :dest_time => '2013-10-21 09:00:00',
+        :diff      => 120,
+        :timezone  => 'Europe/Berlin',
+        :config    => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '9:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
+      # test 16 / wintertime
+      {
+        :start     => '2013-10-21 07:00:15',
+        :dest_time => '2013-10-21 09:00:00',
+        :diff      => 120,
+        :timezone  => 'Europe/Berlin',
+        :config    => {
+          'Mon'                  => true,
+          'Tue'                  => true,
+          'Wed'                  => true,
+          'Thu'                  => true,
+          'Fri'                  => true,
+          'beginning_of_workday' => '9:00 am',
+          'end_of_workday'       => '6:00 pm',
+        },
+      },
+
     ]
     tests.each { |test|
-      TimeCalculation.config( test[:config], nil, test[:start] )
-      dest_time = TimeCalculation.dest_time( test[:start] + ' UTC', test[:diff] )
+      dest_time = TimeCalculation.dest_time( test[:start] + ' UTC', test[:diff], test[:config], test[:timezone] )
       assert_equal( dest_time.gmtime, Time.parse( test[:dest_time] + ' UTC' ), "dest time - #{test[:dest_time].to_s}" )
     }
   end