OK, this is the situation. I'm using Babble for both outbound and inbound calls when I'm travelling around - the headset is plugged into my laptop and as a consequence, when someone rings me, it diverts the ring tone to the headset and not the PC speaker.

Anyone have any suggestions?

Unplug the headset when you're not at the PC?

Believe me, the OP has a very valid question - one does forget to plug/unplug the headset... and when one does forget calls simply remain unanswered.

If someone might know the trick for this 'problem' ...

If you're typically looking at the screen when a call would come in, you might want to look at the options in the "Accessibility Options" control panel under the Sound tab, and see if your program sends the events properly to activate the visual notification of sound.

If you want to activate your internal speakers again, don't really have an elegant way to do that, other than removing the headset from the laptop. If you use a single prong headset (eg, headphones), and you want it attached to the computer so that it doesn't "disappear", can you plug into the mic port? Or likewise, if you use a mic/headphone headset, can you just unplug the headphone portion and then plug it in when you receive a call, just like "lifting the receiver"?