Northern Telecom first marketed and manufactured the product line under the SL-1 PBX or PABX large business telephone system. This evolved from the Meridian Norstar to the Nortel Norstar product line. First in size was the Meridian Norstar 616. This supported 6 incoming CO lines and 16 digital telephone extensions however, caller ID and voicemail were not supported. There is however a retrofit caller ID adapter that would all the passage of Caller ID data to the various M7310, M7324, M7100, M7208 small office telephone sets.