Use your favorite broadcast hybrid with most any phone: old, new, single or multi-line.
It hooks up through the handset connector. With the button out, your phone works as normal. With the button in, the handset is disconnected and your hybrid is on line. The performance of the hybrid is the same as though it were connected directly to the central office line. Connectors are modular phone jacks.
(Note: Will not work with Gentner DH20, DH22, or SPH10 Hybrids.)