The Siberian fixed-line service provider's earnings hit 16.6 billion rubles ($620.6 million) in the reporting period, 5.6% more than in the same period of 2005.
The company attributed the increase to changes in its relations with other operators, expanded client base and Internet traffic, and the development of its mobile phone business.
Sales profit in the reporting period totaled 4.1 billion rubles ($153.3 million), up 45.7% year-on-year. Pre-tax profit gained 142.3% to 3 billion rubles ($112.2 million).
SibirTelecom is Russia's third-largest fixed-line telecoms operator by installed capacity, with 3.4 million active lines, and in terms of revenue. It is a subsidiary of Russia's state telecoms giant Svyazinvest.
The company's area of operations covers about 29% of the country's territory, and 14% of its population.