I am using the ios-swift-pjsua2 project from pj-project and I have a problem. I have integrated pjsua2 into CallKit, and the issue is that I can make 4 calls with CallKit, and the 4th call gets disconnected. I noticed that call_id only goes from 0-3, which means that the 4th call has call_id = 4. So, I am putting it on hold with pjsua_call_set_hold(3, nil, nil). However, why is the 5th call rejected with a busy signal? Where exactly do I need to change max_calls or what should I do after making the change? I tried modifying the file mentioned in the post, but when I run ./configure-iphone and then make dep && make clean && make, I get the following error after make dep && make clean && make:

pjproject-master: Is a directory. Stop.