Russian mobile giant Vimpelcom has announced the successful testing of voice-over-Long Term Evolution (VoLTE) technology in its domestic market, Telegeography.com reported on Wednesday. Named “seamless” by the cellco, the trial was carried out in conjunction with Chinese vendor Huawei.

Vimpelcom has extended its LTE network to St Petersburg and parts of the surrounding Leningrad oblast. At launch, the service is available in a number of St Petersburg districts, including: Vyborg, Kalinin, Kirov, Krasnogvardejskiy, Nevsky and Frunze. It is also available in a number of nearby suburbs. By September 2014 the network is expected to cover 80 percent of St Petersburg.