I have a Uniden cordless phone with answering machine, 900 mhz model number exa 122801. How do I adjust the ringer volume?

For the base station set the ringer switch on the base from high to low. To turn it off select off. You can find that switch on the panel where the phone plugs into the wall on the far left.

The handset is adjusted the same way on the leftside as you are looking at the phone.

Since you neglected to specify the model of your Uniden 5.8GHz cordless system I can only suggest you select it from the list beginning here to download the manual.

Look on page 26 of this user guide for your Uniden EXA-3955 to set date and time.
http://www.uniden.com/pdf/EXA3955om.pdf

If it is like mine....push on one of the volume buttons (up or down,doesn't matter) and the phone will ring. WHILE IT RINGS, push the button again and it should scroll to the next ring option. Keep pushing WHILE it rings to scroll through the ring options.

Adjusting the Ringer Volume
You can choose from four ringer volume settings on the handset (off, low, medium,
and high). With the phone in standby, use the up arrow or the down on the handset to adjust the
ringer volume.

You can find your manual online in PDF format here:

http://www.uniden.com/pdf/TRU9360om.pdf

Without the exact model it is difficult to find the manual.

Here the manual for 900 series/996:Uniden EZI996.

I also quote from manual:

Selecting the Ringer Tone and Volume

Base ringer on/off
The ringer switch allows you to set the base ringer on or
off. If you set the switch to off, you never hear the base
ringer tone.

Base ringer tone
Press the ringer tone button in standby mode to select one of 7 ringer tones.

Base ringer volume
Slide the ringer volume adjuster to set the base ringer volume.

Handset ringer tone and volume
Press the volume up key or volume down key (labeled as the volume/ /+ or volume/ /- key) in standby mode to select one of five ringer tones and volume combinations

Yours is a little different from mine, but maybe this will help some, I hope. On the "talk" side, there is a button (2nd from right on mine) which says "loud" over the button, and "ringer" under the button. Pushing the button once gives you the soft ring. Pushing the button again will give you the loud ring. If you have gone to the loud ring, you will get the loud ring on the first time. Then you can push it again to get you back to the soft ring. I hope this helps.

You can find the manual here:

http://www.uniden.com/pdf/EXAI3248om.pdf

The information you're looking for is on page 40.

Do you know the model #? If so, you can get the owners manual from the the uniden website. Here is a link to the page so you can look for your specific model number. Just click on your model number and it will load the pdf format of the owners manual.

http://www.uniden.com/index/manuals_results.cfm?cat=1