Mobile TeleSystems or MTS is the largest mobile operator in Russia and CIS with over 89.64 million subscribers as of April 30, 2008.

Having started in the Moscow license zone in 1994, МТS in 1997 received licenses for further areas, and began expansion, later entering other countries of the CIS. On October 31 2008, Vodafone announced a partnership deal with MTS, whereby Vodafone services will be available to MTS subscribers; some form of co-branding will follow, and both companies have noted the potential for more efficient purchasing.

The MTS wireless network operates using the GSM standard. It currently holds licences to provide mobile services in 87 out of 89 regions in Russia and the entire territories of Armenia, Ukraine, Belarus, Uzbekistan and Turkmenistan.MTS is currently the biggest mobile operator in Central and Eastern Europe.