The Meriian Norstar, later called Nortel Norstar was a small-office digital PBX introduced by Northern Telecom (now Nortel). It is based on the same internal design and instruction set as Nortel's earlier SL-1 and DMS systems, allowing it to support features such as Meridian Mail, automatic call distribution and other features, but can support a total of up to 192 phones and has limited processing power. In the United Kingdom it is sold by British Telecom, rebadged as the BT Norstar.