Muting the Ringtone and MobileSpeak

Greetings.

First, the obligatory stats: I've an HP iPAQ Glisten phone with Windows Mobile 6.5 and MobileSpeak 4.5.2.

Now, to my question...

How, exactly, do I mut the ringer on this phone so I can hear my caller ID being read by MobileSpeak? The MS manual simply doesn't make sense to me on this point (Spanish to English translation?).

Thanks.