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What Headsets Work with the T10, T10H, or T20?

General Information:

The T10, T10H and T20 are headset telephones that work with analog phone lines (T10/H single line, T20 two lines). These phones usually will not work on a digital line without an analog filter. Both phones feature an on/off switch, tone/pulse dialing, redial, a flash button and a mute switch, as well as tone, ringer and listening volume controls. The T20 also includes a hold feature and three-way conferencing capabilities.


To conference on the T20 place the first call on hold. Next answer or originate a call on the other line; when the second caller answers press the Conference button.

Compatible Headsets (see attachment for pictured headsets):

The T10/T20 headset (A) is a specialized version of the M170 that ends in an RJ9 connector. If the Customer wants a binaural headset, the Chattaway binaural (B) will work, though we only recommend this for light use, as it wasn’t constructed to meet the demands of a 40 hour work week.

NOTE: An H-series headset (C) and Polaris cord (D) will also work with the T10 or T20 (The T10H is a T10 Base with a Polaris cord).

Flash Feature:

The T10, T10H and T20 have a “Flash” button for call waiting. If you subscribe to call waiting and are on a call, you’ll hear a tone in the headset when a second call comes in. Press “Flash” to accept the call. There may be a short pause after you push the button depending on whether the ”Flash” is set to 1, 2 or 3 (1 second, 2 seconds, 3 seconds). To return to the original call, press “Flash” again.


With most office systems, the T10/T20 “Flash” button can be used to transfer a call to another extension. To do this while on a call, press the “Flash” button. When you hear the dial tone, enter the extension number. When the phone rings, press “Flash” again, or hang up to transfer the call.

Hold vs. Flash:

The Hold button allows you to suspend an active phone call on line 1 or 2 in order to activate a second call on the other line. Flash allows you to toggle back and forth between two calls that are coming in on the same line.

Basic Troubleshooting:

1. Can’t hear a dial tone: Make sure all the connections are correct and firmly in place. Next, make sure the AC Adapter is powering on the T20 ok. Test Line 1 and 2 (T20 only) to make sure the indicator light comes on. Test the listening volume on the headset. If you have an additional headset, try testing it on the base

2. Can’t dial a number: Test the Tone/Pulse setting

3. Caller can’t hear my voice: Test the mute button and move the microphone closer to your mouth. If a second headset is available, try using it as well

4. Only one line is working (T20 Only): Make sure you are using the correct cables with the correct Line Jacks. There is a Dual line cord (white flagged) and a Telephone line cord


If you hear a buzzing on the line there are 4 possible causes:

1. The Phone Line: Try another phone on this line

2. The Phone Jack: Try plugging the T10(H)/T20 into another jack

3. The Headset: Try another headset on the T10(H)/T20. If another headset does not buzz replace the original headset

4. The Dial Pad: If you still get the buzz with a replacement headset you will need a replacement unit

Hi, I'm Kyle!

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Kyle Newgent wearing a Leitner office headset

Kyle Newgent
Headset Blogger