Callers can still reach you while you are engaged in another call. A signal alerts you to the waiting call.
You can either ignore or accept the waiting call.
When you accept the waiting call, you can either end the first call or place it on hold and resume the call later on.
You can also bar call waiting or the call waiting tone . 

Accepting a Waiting Call (Camp-On)

Precondition: You are engaged in a phone call and hear a tone (every six seconds). 

Ending the first call and answering the waiting call:

Replace the handset. Your telephone rings.  

Answer the second call. Lift the handset.  

Placing the first call on hold and answering the second call:

Select and confirm. 

Press the key. The LED lights up. Enter the code. 

You are connected to the call waiting party immediately. The first party is placed on hold. 

Ending the second call and resuming the first one:

Confirm. 

Press the key. The LED lights up. Enter the code. 

Replace the handset. "Recall: ..." appears on the screen. Lift the handset. 

Preventing and Allowing Call Waiting (Automatic Camp-On)

If this function has been configured (ask your service technician), you can prevent or allow a second call from being signaled by automatic camp-on during an ongoing call.  

Press the key. The LED lights up 

Select and confirm. 

Enter the code for "off" or "on". 

Turning the Call Waiting Tone On and Off

You can suppress the call waiting tone (every six seconds) for external calls. A one-time special dial tone then alerts you to the waiting call. 

Select and confirm. 

Enter code for "tone off" or "tone on".