MOBILE phone customers face a massive 80pc increase in certain call charges from today.
Meteor and O2 are increasing their call connection charges from 5c to 9c.
O2 customers are due to pay more from today while Meteor customers will face the price hike from August 12.
The Consumer Association of Ireland has slammed the charges as "totally unjustified".
The organisation said that Irish customers were already charged some of the highest mobile phone costs in the EU.
The increase in the changes will affect almost 700,000 prepaid customers of the company while more than 400,000 people have contracts with O2.
Increases on phone charges will also be imposed on people with mobile phone contracts, as these customers will have to pay more once they exceed the monthly voice and text allowances that come with their price plans.
If a customer exceeds their monthly allowance of free calls, the price of making a call will then rise by 35pc.
The EU recently imposed caps on roaming charges that phone companies can impose when people are using their mobiles abroad.
The cost of making a call to the 11811 directory enquiry service is to rise by over 17pc from 99c to €1.17.
And O2 is cutting out a desktop text service where people can download software to their computer and send free texts.
Customers can still avail of free texts via the internet by accessing the O2 website.