Model Assumptions

In general, home phone users may not be aware of every aspect of their phone use. Therefore, in order to assist users and to contribute towards an accurate cost comparison, callcosts.ie uses a number of assumptions in making a calculation. Where possible industry data has been used to develop the assumptions listed below.

When most calls are made

To run a calculation, callcosts.ie needs to know when you mostly use your phone and the home phone calculator provides a number of time periods for you to choose from. The reason why you are asked this question relates to the way in which home phone rates differ depending on the time of day you call. The time periods presented by the home phone calculator have the following associated time of day/weekly distributions:

Breakdown of Weekly Usage
Days	Anytime	Weekend	Monday to Friday Daytime	Monday to Friday Evenings	Monday to Friday Daytime and Evening	Monday to Friday Evenings and at weekends	Monday to Friday Daytime and at weekends
Weekday	70%	20%	80%	80%	80%	70%	70%
Weekend	30%	80%	20%	20%	20%	30%	30%
Breakdown of Daily Usage
Hours	Anytime	Weekend	Monday to Friday Daytime	Monday to Friday Evenings	Monday to Friday Daytime and Evening	Monday to Friday Evenings and at weekends	Monday to Friday Daytime and at weekends
00.00 to 06.00	5%	5%	5%	5%	5%	5%	5%
06.00 to 12.00	25%	25%	35%	5%	15%	5%	35%
12.00 to 18.00	35%	35%	55%	15%	40%	15%	55%
18.00 to 24.00	35%	35%	5%	75%	40%	75%	5%

Here is an example how the distribution works for the 'Anytime' option. If you use 100 local minutes per month and you choose the anytime option, the minutes will be distributed as follows

Weekly Breakdown - 70 minutes (70%) are made during the week and 30 minutes (30%) are made at weekends

Cumulative Daily Breakdown – For the relevant period, 5 (5%) of your minutes used will be between midnight and 6.00am, 25 minutes (25%) are between 6.00am and midday, another 35 minutes (35%) are between midday and 6.00pm and the final 35 minutes (35%) are made betweem 6.00pm and midnight.

Which mobile networks you call from your home phone

Charges for calls to mobiles from your home phone tend to vary depending on which mobile network you call and callcosts needs to take account of this in making a calculation. In order to increase the accuracy of your calculation, callcosts.ie distributes your minutes for calls to mobiles across each of the mobile operators' networks. This distribution assumption is based on each mobile operator's market share as it provides a good indication as to which networks your called minutes are likely to go to. The current market shares used on the calculator for distributing minutes across mobile operators' networks are as follows:

Vodafone 39.9%
O2 33.5%
Meteor 21.1%
3 Ireland 5.5%

Please note that you can alter the distribution of minutes to operators' networks by clicking on the 'Enter More Detailed Usage' button at Step 1 of the calculator (This button is located at the end of the first screen)

Reduced rates for On-Net calls

A number of operators offer free or reduced rates if the person you are calling is also one of their customers. In callcosts you can indicate if the people you call are predominantly with one operator.

If you select yes you will be asked to indicate who that operator is and what percentage of your minutes are to people with the same operator. Then callcosts will apply the operators same network rate to applicable calls. If you do not change this field your calculation will still include an operators same network rates however callcosts assumes that 67.7% of your calls will be to customers who are with eircom and the remaining 32.3% is shared among other operators that feature on callcosts.

Fixed minutes for preferred numbers

Some operators may offer discounted or free minutes for calls to a nominated/preferred number. Typically, such ‘preferred number’ schemes, which can also be called 'friends' schemes can have one or more of the following usage conditions:

they must be a landline number(s)
and they must be nominated by the user and notified to the operator.

There may be a limited allocation of minutes and availability may be restricted to off peak times. Callcosts.ie assumes that 5% of the total minutes you entered in Step 1 qualify for ‘preferred number’ offers if such offers are available from an operator.

Please note: if an operator does not have a 'preferred number scheme' the number of assumed minutes (5%) will go back into the calculator and be rated as appropriate. You should note that it is possible to change the number of 'preferred minutes' entered on the 'Enter More Detailed Usage' screen.

Taking Minimum call charge into account

Home phone operators may charge a minimum charge per call irrespective of its duration. High minimum call charges can have an impact on your costs, particularly where calls are of a short duration.

For example, if a local call costs 1 cent per minute during the day and the operator levies a minimum call charge of say 5 cent, then any call lasting less than or equal to 5 minutes (calculated by dividing the 5 cent by the 1cent and multiplying it by 60 seconds) will incur the minimum call charge, irrespective of the duration of the call. i.e. a 5 second call would incur the 5 cent minimum call charge. Once the duration of the call passes 5 minutes it is charged normally. So the total cost of a 6 minute call in this instance would be 6 cent.

To increase the accuracy of your calculation, callcosts.ie makes two assumptions around minimum call charge

an assumption that a set number of calls need an adjustment to take the minimum call charge into account. (59% local, 33% national, 36% mobile & 20% international)
an average call duration assumption that converts the minutes you have entered into a number of calls - as the minimum charge is levied per call rather than per minute. (local 4 minutes, national 6.5minutes, mobile 2 minutes & international 7 minutes).

International destinations on callcosts

Callcosts.ie features a list of the most popular destinations for International calls. These destinations are Australia, Canada, France, Germany, Italy, Netherlands, Poland, Spain, UK, UK Mobile and USA.

Plans with Carrier Pre-Selection

In the home phone section, the results provided all include line rental costs, however some operators offer call only tariff plans which mean you keep eircom as your telephone line provider and the alternative operator charges you for calls. This is called Carrier Pre-Selection or CPS. If you have this service you will receive a bill from both your line provider and your calls provider. For a fair comparison on callcosts the eircom standard line rental charge is included with CPS plans.