At the same time, net income of the company fell by 20.2% from US$30.7 million in the first quarter of 2009 to US$24.5 million in the same period of 2010.

OIBDA decreased 6.6% year-on-year from US$60.5 million in January-March 2009 to US$56.5 million in the same period of 2010. The company said OIBDA margin fell from 59.5% in the first three months of 2009 to 54.6% in the first quarter of 2010. Operating income before depreciation and amortization (OIBDA) represents operating income before depreciation and amortization. OIBDA margin is defined as OIBDA as a percentage of net revenues.

ARPU made up US$4.8 in the first quarter of 2010, while it was US$5.8 in January-March 2009. Average monthly service revenue per subscriber (ARPU) is calculated by dividing service revenues for a given period, including interconnect and guest roaming fees, by the average number of our subscribers during that period and dividing by the number of months in that period.

The MOU grew from 416 minutes to 520 minutes in the reporting period. Average monthly minutes of usage per subscriber (MOU) is calculated by dividing the total number of minutes of usage during a given period by the average number of our subscribers during the period and dividing by the number of months in that period.

SAC fell from US$8.2 in the first three months of 2009 to US$6.1 in the same period of 2010. Subscriber acquisition cost (SAC) is total sales and marketing expenses and handset subsidies for a given period. Sales and marketing expenses include advertising expenses and commissions to dealers.

Number of subscribers of MTS Uzbekistan grew from 7.07 million in the first quarter of 2009 to 7.38 million in the same period of 2010.

The capital investments of MTS in Uzbekistan totalled US$23.9 million in January-March 2010 against US$87.4 million in the same period of 2009.