Yes and yes and of course! :o) Here’s how:

Open the Messenger menu, and click Preferences.

Click "Alerts & Sounds".

After "Alert me when", select "I receive an incoming voice call".

The available ringtones are listed below. You can hear each one by double-clicking it, or clicking it once and then clicking "Play."

Creating a custom ringtone:

Any sound file with a WAV extension can be used as a custom ringtone.

You can find and purchase lots of .wav files on the web, and you can even record your own.

All you need to record your own ringtone is a microphone attached to the audio in jack of your PC, and the Sound Recorder application that comes with Microsoft Windows (Start Menu > Programs > Accessories > Entertainment > Sound Recorder). Open Sound Recorder and, when you’re ready to record, just click the red-circle button (Record). Click the black square button (Stop) to stop recording.

Click File then Save, and be sure to make note of where on your hard drive you save the ringtone.

Now, in Messenger, go to Preferences.

Click "Alerts & Sounds".

After "Alert me when", select "I receive an incoming voice call".

Click "Import" to add the WAV file to your list of ringtones. That’s it!

Note: If you’re having problems importing a ring tone, please make sure that .wav is at the end of the file name.

Assigning a ringtone to a contact on your Messenger List:

On your Messenger List, click the contact for whom you’d like to designate a specific ringtone. This highlights their name.

At the top of the Messenger window, click Contacts.

Move your pointer over "Ringtone", and click the desired ringtone.

Or, right-click the contact. That opens a menu that includes "Ringtone," from which you can select the sound you want!

Setting your default ringtone:

Click Messenger, then Preferences.

Click "Alerts & Sounds".

After "Alert me when", select "I receive an incoming voice call".

In the ringtone area, click once on the ringtone you want to use, and then click Set Default.

Note: To disable ringtones so that NO ringtone will be played when you receive a call, un-check the checkbox labeled "Play a ringtone when I receive a call." You’ll still be notified when a call comes in. A boxing glove will suddenly emerge from your screen to pat you on the nose three times: one—two—three. No, but seriously! A pop-up box will appear showing the name of the caller, with buttons giving you the choice to either Accept or Decline the call, or to IM Only with the caller.