I have many DT700 series SIP phones, and I have a situation where I need to connect a loud-speaker (or amp) to the phone, so a bigger audience can hear a phone converastion in a conference room. There are many different connectors on the bottom-side of the phone and I would imagine NEC made those for certain adaptors. I'm really just looking for an analog output of the phone conversation on a standard earphone-type connector that I can connect to the amplifying system. And the audio would be output even if the phone-conversation happens using the speakerphone (ie, the radioshack recording adapter that connects to the handset cord, is out-of question).
Does such thing exist?

Does the phone system reside in your building? Because you are MUCH better off getting a Polycom conf phone.

I have tghe system inside the building. But I can't use anything but a DT700 SIP phone and I need an analog output/adapter for this. I came across this since I posted my question:

https://www.telecomcreations.com/NEC_ADA_L_UNIT_DT330_DT730_DT750_ADA_Adapter_p/680601.htm

I'm getting one to test, and it really looks like exactly what I need.

This was exactly what I wanted: an NEC-made adapter, connecting to a pre-made connector on the bottom of the phone, providing an analog audio output port, as well as an input port in order to inject auctio into the phone conversation. Works like a charm!