The Silent Ringtone
Download the silent ringtone as either an MP3 file or a WAV file if you want your cell phone to ring without a sound. With a silent ringtone your phone will ring but no one else can hear it.
Configure your phone to vibrate when a call or text comes in as well as use the silent ringtone. You can feel it; no one else can hear it.
Try the Mosquito Ringtone too.