The "BITEL" from Siemens is the first on-screen text phone that was approved by the Bundespost for connecting to private branch exchanges and main lines. It combines telephony and the BTX service in one device. The "BITEL" had a 7-inch black and white tube with storage for up to 400 names and numbers, and could be purchased or rented. In 1987, a BITEL cost between DM 2,500 and DM 2,700. Renting it cost DM 78 per month.