Telefonica Deutschland Holding is a telecommunication company. Co. offers its consumer retail and business customers postpaid and prepaid wireless communications products, along with wireless data services using Global Packet Radio Service, Universal Mobile Telecommunications System and Long Term Evolution technology as well as Digital Subscriber Line wireline telephony and high-speed internet services. Co. markets its products and its wireless and wireline communications products as well as services via the core brand O2. Co.'s secondary brands include the brands Fonic and netzclub. Co. also markets high-speed DSL internet access and wireline telephony.

Telefonica is engaged in the provision of public or private telecommunications services, including ancillary or complementary telecommunications services or related services. Co.'s fixed business includes: traditional fixed telecommunication services, Internet and broadband multimedia services, data and business-aplications services, and wholesale services for telecommunication operators. Co. also provides a range of mobile and related services and products to consumer and business customers, including mobile voice services, value added services, mobile data and Internet services, wholesale services, corporate services, roaming, fixed wireless, and, trunking and paging.