Explosion Proof Phone Call Waiting Yes Overall Depth 135 mm Speakerphone Yes Overall Height 266 mm Overall Width 227 mm Volume Control Yes Standards EN60529 Number of Handsets 1 Number of Lines 2 Mounting Location Surface Wall Caller ID Yes Enclosure Rating NEMA 4X Includes Mounting Hardware Yes Maximum Operating Temperature 140 Degrees F Minimum Operating Temperature -13 Degrees F Color Black Resistance Properties Explosion Proof Weatherproof