Telephone Features Single Line Corded Integrated Telephone and digital answering machine system with speakerphone / 3-Line LCD with Call-ID Display - Tapeless Digital Answering System - 2-Way Recording - Caller ID display - 3 One-Touch Memory Buttons - 3-Line Dot-Segment LCD - Ringer Indicator (LED) - Redial (up to Last 20 numbers Dialed) - Electronic Handset Volume Control ( 4-Step) - Electronic Speaker-Phone Volume Control (8-Steps) - Table or Wall Mountable - Tone/pulse Settings - Programmable 4-Step Ringer Selector - Redial/Mute/Pause/Hold/Flash functions - Headset Jack for adding an Optional headset - Data Port   Headsets Features     General Product Type Headset Color Dark gray Recommended Use Cellular phone Additional Features Mute button, Noise canceling circuit Localization English Headphones Headphones Type Headphone - Monaural Headphones Form Factor Convertible Connectivity Technology Wired Sound Output Mode Mono Response Bandwidth 300 - 3300 Hz Impedance 150 Ohm In-Cord Volume Control Yes Microphone Type Built-in Microphone Technology Electret condenser Microphone Operation Mode Mono, Cardioid Connectivity Technology Wired Impedance 3.3 KOhm Microphone Power Source Voltage (DC) 3 V Audio Input Details Cardioid - 300 - 3300 Hz - Output Impedance 3.3 KOhm Remote Control Type None Connections Connector Type 1 x Headset ( Sub-mini phone stereo 2.5 mm ) Miscellaneous Cables Included 1 x Audio cable - Integrated - 4 ft Power Power Device None Battery None Manufacturer Warranty Service & Support 1 year warranty Service & Support Details Limited warranty - 1 year Mute Jack 2.5"