With its investment in Slovenia's Si.mobil d.d., mobilkom austria continued its Central- and Eastern European expansion. In February 2001, mobilkom austria acquired majority ownership of the company, which began operating in March 1999 as Slovenia's first private mobile service provider. Since May 2006, mobilkom austria has held a 100 percent interest in Si.mobil.

After the mobilkom austria group signed partnership agreement with Vodafone, Si.mobil also strengthened its marketing cooperation with one of the world's largest mobile operators. From September 2003 on, all market-oriented activities are presented under the dual-brand Si.mobil-Vodafone. The move to dual-branding was introduced with the new slogan "Catch the world", promising more fun and success in a global world. Si.mobil-Vodafone presents a wide range of global products and services, and an expanded roaming network.

Si.mobil was the first operator in Slovenia to offer GPRS and one of the first operators worldwide to launch EDGE, which enables much higher data transfer speed. Since September 2007 Si.mobil-Vodafone has offered UMTS to all customers.