The Merlin 10 Button HFAI Phone Model # 7309H 10btn HFAI has LED indicators for line appearances and programmable features. The Merlin 10 Button HFAI handsfree phone 7309H 10btn HFAI features include conference, transfer, hold, drop, and recall. There is a 2-way speakerphone capability with use of the intercom feature, but otherwise monitor speaker is available only. Compatible with Merlin 206, 410, 820, 1030/3070, Merlin II, Merlin Plus, Merlin Legend and System 25. As Business Phone Systems go, the Merlin Business Phone Systems have been around for a very long time and are still in active use.