Answer:

The Spirit 308 has the capabilities of supporting a total of 3 incoming lines(telephone numbers) and 8 total system extensions.

It also has:

• 1 External Alert Jack
• 2 Line Aux Jacks
• 1 Paging Jack
• Music On Hold Jack (RCA)

A 616 Expansion Unit can be added onto the existing Spirit 308. This will add 3 more lines and 8 more extensions. It will also provide another Line Aux Jack. External Alert, Paging, and Music On Hold Jacks are not provided with the expansion unit.