VIBER WHATSAPP WECHAT FACETIME SIP GATEWAY

Hello, We need to develop a SIP to Viber, Whatsapp, WeChat and Facetime gateway. The gateway should be able to pass voice calls incoming over SIP and forward them through Viber, Whatsapp, WeChat and Facetime to complete the call to the called party number. The development platform/operating system is not important. The project should be completed by using the Linux server. The implementation should return the correct call error codes to the SIP backend, i.e. CALL SUCCESS, BUSY, UNAVAILABLE, etc. For a successful project we'll select the one, triggering successfully continuous SIP to Viber, Whatsapp, WeChat and Facetime calls. Functional flow 1) Calls originating will send to Viber, Whatsapp, WeChat and Facetime gateway 2) Viber, Whatsapp, WeChat and Facetime gateway converts the sip/iax signal to viber protocol 3) the termination number carried from the origination header will be checked by the Viber gateway , if the number is used by Viber, Whatsapp, WeChat and Facetime and if the number is online, the call will terminated on Viber, Whatsapp, WeChat and Facetime. 4) if the number is not used in Viber, Whatsapp, WeChat and Facetimeit sends 503 error and rerouted to other gateways .