Customers on pay monthly mobile phone contracts with Orange and T-Mobile will have to pay 3.3 per cent more in future, as a result of inflation.
The two operators, which merged in 2010, said the price hike will typically result in most pay monthly customers having to pay around 70p extra a month.
The price hike has been blamed on inflation and will come into effect on 10 April 2013 for Orange customers, and for T-Mobile users on 9 May 2013.
We know price rises are never great news, but we always aim to offer great value to our customers.
However, customers that have recently joined T-Mobile will not be affected by the price rise until November 2013, and neither will those that have recently signed up for Orange's new Animal or The Works payment plans.
"All other charges outside your allowance, such as call costs, text and bundles, stay the same," the companies said in post on their respective websites.
In a statement to IT Pro, the companies said customers will also have the option to fix the price of their monthly contracts.
"We know price rises are never great news, but we always aim to offer great value to our customers as well as the best service on the UK's biggest network," it stated.
"We have listened to our customers and understand that some would like the option of fixing the price of their monthly plan. That's why we are launching a Fix You Monthly Plan' option the first of its kind in the industry," the statement added.
The scheme will reportedly ensure end users continue to pay the same amount each month for the duration of their contract, even if further price rises are introduced.
Pricing for the plan starts at 50p per month for people who pay up to 14.99 a month for their T-Mobile or Orange contract, and will cost up to 2.00 a month for people on 35 a month deals.
The operators aren't the only ones to have increased their prices in line with inflation recently, as O2's pay monthly customers were recently hit with a 3.2 per cent price jump that came into effect at the end of last month.
