Ringer not loud enough

https://www.telstra.com.au/aboutus/community-environment/community-programs/disability/disability-equipment-program
or google search extension ringer
the above link under accessories shows an example of an extension ringer for deaf/ hard of hearing customers

Two different options,... Call the extension, and while it is ringing, press the volume down bar until you can no longer hear it ringing. You can also try this... Leaving the handset down, do Feature * 80, adjust the loudness for ringer volume by pressing the volume bar.

Why not ask Comdial customer support

If the ringout volume is very low, then try not to select a soft, silent or low ringing tone. Try to choose a ringing tone that is loud so that you can hear your phone ringout.
Hope that was helpful?

try an external phone ringer. some have flashing light, extra loud ringer, vibrating option

http://www.smithgear.com/phone-ringers.html

The problem is with your "Ringer" (the bigger speaker). If you can hear the sound through your ear piece, then replacing the Ringer/Speaker will definitely fix your problem. I would suggest to get it done from a service center or from a mobile repairing shop.
Good luck.

Thanks for using FixYa.

Is the phones ringer turned up? It needs to be loud enough to make the ring detector ring.....

You can set the length of your incoming ring to in the Call forwarding portion of the phone. Usually, it is set to 25 seconds. It can go as high as 30 seconds. To set the ringer to be longer or shorter, it goes by 5,10,15,... set of 5 increments. up to 30.
I would also recommend to use a factory set ringtone, set the profile to LOUD or OUTDOORS. With vibrate option on. Some downloaded ringtones don't play as loud.

You didn't indicate exact model of your phone. However I have indicated the procedure used for common Vtech's 5.8Ghz phones

Ringer volume
• With the handset or base in idle (off) mode, press MENU then
press ▲ or ▼ until RINGER VOLUME is shown
• Press SEL. You will hear a sample of the ringer
• Press ▲,▼ or a digit (0 through 6) You will hear a sample of
the new ringer volume and the volume bar will be increased or
decreased each time the setting is adjusted At the lowest setting
the ringer will be turned off and the display will show:
- OR -
• With the handset or base in idle (off) mode, press or of the
volume control will directly go to ringer volume menu
• Press ▲ or ▼ to adjust the ringer volume

Good Luck

It's in your settings. Just try to change the ringing mode. Set plain instead of ascending