BT customers will have to pay up to 10% more for phone calls on their landline, the company confirmed.
The telecoms giant, which has 12.5m phone customers, said it would also increase its monthly line rental by 50p from the beginning of October.
Letters informing people of the changes will be arriving on their doormats this week.
The cost of connecting a call will go up from 9.9p to 10.9p, while the daytime rate rises from 5.9p to 6.4p per minute.
BT said it estimated the impact of the changes would amount to 1p a day because its average customer makes only 80 seconds of daytime calls each day and more than half subscribe to inclusive packages.
Customers could also save money by signing up to 12-month line rental contracts upfront, according to the company.
The firm warned customers that from October, they will have to pay a landline rental charge of £13.29 a month, or £12.04 if they receive their bills by e-mail.
After October 1, the standard cost of a landline will be £159.48 - or £131.88 for people who pay the full sum upfront.
A BT spokesman said: "The calling patterns of customers means the impact of the daytime rate and set-up fee changes will be minimal.
"More than half our customers are on inclusive calling packages and don't pay charges for most calls.
"We are happy to discuss with customers the savings they could make with Line Rental Saver and an inclusive calling plan - 3.9 million people signed up to plans in the last year and only 34% of UK landline calls are paid for directly."
It was necessary for the company to review prices to cover costs and emerge from recession in "good shape", the spokesman added.
He said BT tried to protect customers from high prices and maintained its charges were "very competitive".