Asterisk SIP Infrastructure Setup

I have most of the mobile application ready; what I still need is a solid Asterisk-based voice layer that simply works every time a user places or receives a call. My priority is configuration and integration:... (Budget: ₹1250 - ₹2500 INR, Jobs: Android, API Development, Asterisk PBX, Linux, Mobile App Development, SIP, Telecommunications Engineering, VoIP)