The E-10A-EWP is a telephone line powered entry phone designed to provide two-way handsfree communication. When the "Call" button is pressed, the E-10A-EWP will come off-hook and will remain off-hook until a CPC signal is detected, the programmed timeout has elapsed, a busy signal is detected, or the call goes silent, making the unit automatically disconnect.

The E-10A-EWP can be used with a Viking K-1900-5 or K1900-30 dialer, or connected directly to a CO line or analog PABX / KSU station when programmed as a ringdown circuit. If a line or station is not available, a Viking DLE-200B ringdown circuit can be used. One to four E-10A-EWP speaker phones can share an existing phone line in a house or small business when used with a Viking C-200, C-250 or C-2000B Entry Phone Controller.