public CallHistory GetCallHistory(int telephoneNumber)
        {
            var calls = _data.GetInformationList().
                        Where(x => x.Number == telephoneNumber || x.TargetNumber == telephoneNumber).ToList();
            var callHistory = new CallHistory();

            foreach (var call in calls)
            {
                TypeOfCall callType;
                int        number;
                if (call.Number == telephoneNumber)
                {
                    callType = TypeOfCall.OutgoingCall;
                    number   = call.TargetNumber;
                }
                else
                {
                    callType = TypeOfCall.IncomingCall;
                    number   = call.Number;
                }
                var callRecord = new CallRecord(callType, number, call.StartOfCall, new DateTime((call.EndOfCall - call.StartOfCall).Ticks), call.CostOfCall);
                callHistory.AddCallRecord(callRecord);
            }
            return(callHistory);
        }
 public void AddCallRecord(CallRecord record)
 {
     CallRecords.Add(record);
 }