O2, the smallest of Germany's four mobile operators, will begin offering a flat-rate tariff for mobile phone calls during the second half of November, a report from Financial Times Deutschland said.
The report said the company would be the last German cellco to launch this kind of service, which was pioneered by E-Plus.
E-Plus had been offering a flat-rate tariff under its Base brand since August 2005, the report said.
According to the report, O2 said Base customers brought in almost 50 euros in turnover each month for E-Plus, considerably more than customers of other tariffs.
Having previously been fiercely opposed to flat-rate tariffs, O2 now admitted that it must follow the market and that these tariffs were not merely a passing phenomenon, as the mobile operator had thought at first, the report said.
From October 27 onwards, O2 also planned to focus on business with fast DSL Internet access, to ensure that it would continue to achieve strong growth, the report further said.
In the long term, the report said the company hoped to gain up to 20% of business with new customers in Germany, although the group's tariffs for DSL access were currently average for the market.