I am looking for developer who has experience in VoIP SIP technology for developling mobile app. Can use CSIPSimple or PJSIP stack for developing simple communication application for our business internal use. We will be using Asterisks server as communication medium. Application prime function is to call another registered party. App should be capable for sip to sip, sip to phone calling, texting and audio messages transfer. Registration of user client should be simple using easy signup wizard. App should also be able to access contacts of the device and send them message to signup. User can call each other using their extension numbers or screen name (screen name can be based on phone contact list names). Contact invite is needed where the user can invite other person through sharing button and sharing can be via other installed apps on user device such as email, gmail, whats app etc.
Initially we will take Android app and later on we will also needing IOS app. Low bandwidth codecs are required. Video calling is not required. We will require source code of the project.