Telephone volume...

My home phone sits right next to me on the computer desk - hence I have the volume turned down low, always have...
However
Someone, somehow has turned it to full volume and it just rang and it is deafning.
I can't find anywhere how to 'turn it down' again - and of course everyone in the house is innnocent and "Didn't touch it"
It's a Telstra display phone.
If anyone has any idea about how to turn the darn thing down, please let me know.
Thankyou
However

Someone, somehow has turned it to full volume and it just rang and it is deafning.
I can't find anywhere how to 'turn it down' again - and of course everyone in the house is innnocent and "Didn't touch it"

It's a Telstra display phone.
If anyone has any idea about how to turn the darn thing down, please let me know.
Thankyou
