If your DuraFon handset is already at volume level 6 and still isn't loud enough, there's an internal service menu with additional audio adjustment that most users never see. Here are the three procedures — speaker output, secondary volume, and microphone sensitivity — with the exact key sequences.
Quick answer
Last updated July 2026
Before you start
These procedures access an internal service menu, not the standard user settings. Two things worth doing first:
- Confirm you've already tried the normal volume control and set it to 6. These adjustments are only for when the standard maximum still isn't sufficient.
- Write down the current value before you change it. Since this is a service-level setting, noting the default gives you a way back if the new value sounds worse rather than better.
Myth
On the DuraFon Codec settings, a higher number means louder.Reality
It's the opposite. On both the Codec Out (speaker) and Codec In (microphone) tests, zero is the loudest setting and 9 is the quietest. Default values typically sit between 3 and 5. If you increase the number expecting more volume, you'll get less — so adjust downward toward zero to make it louder.Handset speaker output (DuraFon 1X, 4X, and PRO)
This is the main adjustment for making the earpiece louder:
- Press Menu, *, *, # (star, star, pound).
- Press Option 2 for "Boardtest."
- Press 41 to enter the "Codec Out" test.
- Note the digit in the bottom right corner — the default is typically between 3 and 5.
- Adjust the value. Remember: zero is loudest, 9 is quietest.
- Press End to finish, then End again to exit.
Secondary speaker volume (DuraFon 4X and PRO only)
The 4X and PRO have an additional volume adjustment the 1X doesn't:
- Press Menu, *, *, # (star, star, pound).
- Press Option 4 for "Vol Adjust."
- Use the up/down arrows to move between -8, -4, 0, +4, and +8.
- Here the scale runs the intuitive way: +8 is loudest, -8 is quietest, and the default is zero.
- Press the top left button to save.
- Press End three times to exit.
Microphone sensitivity (DuraFon 1X, 4X, and PRO)
If callers can't hear you clearly rather than the reverse, adjust the microphone instead:
- Press Menu, *, *, # (star, star, pound).
- Press Option 2 for "Boardtest."
- Press 51 to enter the "Codec In" test.
- Note the digit in the bottom right corner — the default is typically between 3 and 5.
- Adjust the value, again with zero loudest and 9 quietest.
- Press End to finish, then End again to exit.
How do I make my DuraFon handset louder than volume 6?
Enter the service menu with Menu, *, *, #, select Option 2 "Boardtest," then press 41 for the Codec Out test. Adjust the value in the bottom right corner — zero is loudest, 9 is quietest, with defaults typically between 3 and 5. Press End twice to save and exit.
Why did my DuraFon get quieter when I raised the number?
Because the Codec scale runs backwards from what you'd expect: zero is the loudest setting and 9 is the quietest. To increase volume, adjust the number downward toward zero.
How do I adjust the microphone if callers can't hear me?
Use the Codec In test rather than Codec Out: press Menu, *, *, #, then Option 2 "Boardtest," then 51. The value in the bottom right corner controls microphone sensitivity, with zero loudest and 9 quietest.
Does the DuraFon 1X have the secondary volume adjustment?
No. The Option 4 "Vol Adjust" setting (ranging from -8 to +8) is available on the DuraFon 4X and PRO only. The 1X has just the Codec Out adjustment under Option 2.
These adjustments solve most "still not loud enough" situations on a DuraFon system. If you've worked through them and the audio still isn't right, call our team at 877-999-3838 — and note your current Codec values before you call, since that tells us where you're starting from.
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