The Nortel / Norstar business telephone system is one of the most robust and reliable business telephone systems available. With systems as small as 3×8 (3 incoming central office telephone lines and 8 telephone or work station locations) up to multiple DS1 and hundreds of stations, the Nortel / Norstar systems can handle your needs.
If you are new to installing a Nortel/Norstar telephone system and you are installing a complex system, it is recommended that you hire an experienced installer for the initial set up. This site is a good resource for information and for expansion/replacement parts.
The simple 3×8 systems can be purchased and installed by many small business owners.
Be aware that the the “M” telephone units and the “T” telephone units are not interchangeable. Before you buy a replacement unit for your system that will not be useable.