The Envoy Mixer includes
4 microphone inputs on standard XLR connectors. Two of these inputs are mic/line switchable.
The 4th mic/line input can be routed to the main program mix... or just to the headphones for local cueing.
3 headphone outputs on 1/4" phone jacks. Headphones may be set up for either a mix or split feed of local and return audio.

PLUS
A separate line level output on XLR can feed a PA system, recorder, etc. This output may be muted with a front panel push switch.
The outputs are an externally controllable mix of local program audio and studio return.
Program inputs may be muted with a single front panel push switch.ck

features
Quick-dial memory feature allows one button dialing of up to 20 pre-stored numbers, plus last number redial.
Specific ISDN information, including SPIDs, switch types and LDNs, may be saved for up to 10 different sites.
The Envoy automatically adapts to answer ISDN calls at 56, 64, 112 or 128 kb/s.

And more cool stuff
The Envoy includes an ancillary data channel of 4800 baud, allowing a user to pass data between two computers... great for call screening or delivering sports scores.
A contact closure is available on the Envoy which is automatically enable upon connection.
An internal peak limiter is included.

Low delay
The coding delay is only 6 milliseconds to allow free-flowing, interactive communication.