how to tell if there is an incoming call during a conversation already in progress?
Are you referring to an incoming voice call when MO/MT voice call already in progress?
If so, please first make sure call waiting feature is supported by carrier SIM, then use +CCWA to enable the feature in module and use +CHLD to switch between both parties.
Kindly refer to AT command guide for details.
CONTINUOUS NOT SEE THE SECOND INCOMING CALL
The topic has been moved to the correct section.
Sorry for come back lately.
In my case, using wismo228, I can see RING when call is already in progress, and I am able to switch both call using +CHLD.
AT+CCWA=0 OK RING ata OK RING RING
So, what’s the exact issue on your side?
Have you confirmed that your SIM subscription support call waiting feature or multiple call?