To better serve my clients I have added The Jk Audio Compack phone interface and dial box. After much research this is the most flexible phone interface available because it allows for recording conversations and IFB dialing in any situation it will work with all the following:
Cell Phones: Simply plug ComPack into the 2.5 mm headset jack of your wireless cell phone. Your phone will recognize ComPack as a headset which will disable the mic and speaker in the phone.
PBX Systems: Unplug the handset from any analog or digital PBX phone and plug the coily cord into ComPack. You can now send and receive audio through the PBX telephone set.
Analog Phones: Plug ComPack into an RJ-11 jack, go off-hook and dial, or answer an incoming call.
So far it has done a great job and I am sure will serve me well for many years to come