Asterisk on Andriod as Call app

Hi: i have installed Asterisk on Centos distribution on Samsung s7 edge (rooted) using Linux Deploy app . Now we have Asterisk on an Android mobile phone . As i saw many calling app , like skype or other calling app's , can give choices to user to call over SIP or internally through app or use GSM (local GSM network on mobile phone) if GSM option is selected ,call will be processed over GSM network . My main Goal is not to Build calling app , but to configure Asterisk instead of the calling app , in order to make Asterisk send call over GSM , so: -Asterisk is already installed on Andriod . - Need someone to Develop an Asterisk channel or converting the sip call sent by asterisk to be received by GSM software of the phone, to stream 2 way audio , also to detect call status (busy,answered,Hangup,rejected) I have some examples i found on Google to people trying to make calling apps to call over GSM but sure the one i want isn't App , its Asterisk PBX , so i just want to give the freelancers an Idea to what iam asking for it , Please take a Look to the text file attached , thanks. Needed Experiences should be Android Developer with an Asterisk Developer .