BT is now charging customers £11.27 a month instead of £10.27, while TalkTalk has increased its line rental to £11.25 from £10.50 per month.
"Unlike gas, food, electricity or virtually any other household bills, the price of telephone calls has been coming down - by a third over the last five years," said BT justifying the price increase.
It also revealed vulnerable customers on BT Basic "are protected from these increases" and will continue to pay "a subsidised line rental of just £4.40 a month".
Michael Phillips, product director, of comparison site HomePhoneChoices.co.uk said: "This price increase is very disappointing, bills should be getting cheaper given the current state of their customers' finances in the midst of the credit crunch".
"BT sets the agenda in the home phone market, so I won't be surprised if we see smaller providers follow suit and hike up their own line rental charges," he added.
BT also said it was "giving back more than £200m worth of price cuts, including free calls to 0845 and 0870 numbers for 14m customers, as well as offering cheaper calls to mobiles and international numbers".
"Of course no-one wants to pay more in hard times, but if you look at what we have on offer there are great savings to be made. The vast majority of our customers could save £15 a year by having an online bill. Around five million of our customers could save another £18 a year by paying through direct debit, which is safe and convenient."
However, Phillips slammed both ISPs for charging customers extra for not opting for paperless billing and BT 's practice of penalising customers with a £1.50 charge if they don't pay by Direct Debit.
"We would definitely recommend that customers pay by direct debit and opt for paperless billing. If you can't pay by direct debit then the Post Office accepts payment by cheque, cash or over the phone with no additional charge and no minimum contract period."
TalkTalk said: "BT is increasing its line rental charge on the 1st April so our increases are in line with their charges. As part of these changes, from May 2009, we are offering our customers free local calls at anytime and calls to 0870/0845 numbers as part of their call plan so the majority of our customers will actually be better off as a result of these changes".