Build app similar to linphone /neophone. Able to run off and open source program to charge to use our ippbx. Sip trunks. (THERE IS NO ADVANCE PAYMENT ). No milestones no nothing payment on full completion ......... We are a UK plc
10 freelancers are bidding on average $790 for this job
very lucky, I had just developed a sip application using linphone SDK for iPhone/ android . :) If you have interesting on it, I can send you the application.