GSM services
On July 1, 1992, Deutsche Bundespost Telekom's "DeTeMobil" subsidiary began operating Germany's first GSM 900 MHz frequency cellular network, which the organization referred to as "D-Netz". Digital GSM services were marketed under the "D1" brand and DeTeMobil continued to sell analog cellular services concurrently under the existing C-Tel brand. In 1994, DeTeMobil introduced short message service (SMS) services.