I am using SIM900A card and currently working on AT commands. I am trying to get caller number when I am already in another call. In theory I should get "CLIP+ number", this only works when I am not in communication. During a call, when someone calls me, I get "RING". I want the number of the second caller..
I got an answer, I thought someone might benefit from it. I actually used AT+CLCC which show my calls log. From this log I extracted the number using substring. This document helped me a lot : https://www.usr.cn/Down/Development/USR-GPRS-AT_Commnad_Set_V5.00.pdf