This entry system is designed to utilize a building’s existing telephone wiring and to address a variety of apartment entry applications.  Viking’s  C-3000 Entry System provides secure multi-tenant building access, without the need for any C.O. lines; the only requirement is that each tenant have a touchtone telephone set wired to their apartment.  The  C-3000 performs equally as well in installations where C.O. lines are present. An  individual  C-3000 module has a 12-tenant capacity; for larger applications, a maximum of eight (8)  C-3000 modules can be interconnected, allowing a total system capacity of up to 96 tenants.  A C-3000 system consists of at least one Master  C-3000 module, and as many as seven Slave modules. From either of two entry doors, visitors may ring a tenant's telephone with a distinctive cadence, alerting the tenant of their arrival.  The  C-3000 provides call waiting tones if the tenant’s line is in use.   The tenant may then converse freely with the visitor via their existing telephones. Once identified, the tenant can let the visitor in by entering a single touch-tone on the keypad of the tenant's telephone set. The  C-3000 keyless entry feature supports unique entry codes for each tenant.  As a measure of security, the codes can be easily changed as tenants move in and out of the building. A postal lock feature is also supplied as an added convenience. A