The European Commission gave British Telecommunications Plc the final go-ahead for its investment in and joint venture with MCI Communications Corp yesterday. The Commission said the joint venture did restrict competition but that an exemption was warranted because it offered significant advantages to consumers. Concert would be able to offer more advanced services than either British Telecom or MCI could provide alone and would also substantially reduce the costs and risks associated with offering the scale and features required by big international users. The Commission won assurances that any user in the 17-country European Economic Area can obtain Concert’s services through MCI, even though BT will be appointed exclusive distributor; MCI will be dissuaded from entering some European markets for only five years; the exemption runs to 2000.