This requires to write a Analog Feature Test script with the following actions:
1. A call B, DTMF with path confirmation once
2. C calls A.
3. A: wait for tone (The tone frequencies must be matched with the Call Wait (CW) tone coming from the switch. You got to specify both two frequencies. If your CW tone is a single frequency tone, enter the same on both.
4. A: Wait for CIDCW. This is a special action available in the Action --> Wait --> Caller ID during Call Waiting.
5. Other actions as needed.
User must configure in the own phone book the CNAME and CNUM for Caller ID verification purpose. Special attention must be paid on the detection of Call Wait tone and CIDCW alert tone. These tones are sent at a reduced level to avoid the unnecessary disturbance to the call in conversation. Hence user may need to adjust the tone detection level (available in the Channel --> Terminate Subs --> Detect Thresholds" )and Gain to accommodate the low tone levels.