It takes at least 2 rings for the phone to receive CID information and announce it. If the phone is answered before the end of the second ring, the phone won't announce the name of the caller. 
Adjusting the Base Visual Ringer
You can change the brightness of the base visual ringer. The Visual Ringer switch is at the top of the base (above the cradle). Slide the switch to High, Low, or Off. (It doesn't affect the audio ringers.)
Using the Audio Boost
You can increase the earpiece volume for normal calls and intercom calls. During a call, press Boost. Press Boost again to turn off.
Silent Mode
You can silence the ringers on the base and all handsets at the same time. It doesn't affect the visual ringers.
With the phone in standby, press and hold Silent on the base. The phone automatically turns on the answering system and shows Do Not Disturb in the display on each station. (The answering system answers any incoming calls without playing anything through the speaker.)
To cancel, press Silent again.
##If you turn the answering system off while Silent Mode is on, the phone turns off Silent Mode.
Using Multi-Station Features
##To use the features in this section, you need at least 1 cordless handset.
Expanding Your Phone
Your base supports a total of six cordless handsets, including any that came with your phone.
You must register accessory handsets to the base before using them. Handsets that aren’t registered display a "not registered" message. For registration instructions, see p. 24, or the accessory handset manual.
Using Conference Calling
When an outside call comes in, the base and two cordless handsets can join in a conference call with the outside caller.
To join the call, just pick up the corded handset from the base or press Talk/ end on a cordless handset. To leave the conference call, hang up normally; the other station remains connected to the call.