We need to develop a SIP to Viber/Whatsapp gateway. The gateway should be able to pass voice calls incoming over SIP and forward them through Viber/whatsapp to complete the call to the called party number. The devolpment should run under GNU/linux (Asterisk,etc). 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/Viber calls.
1) Calls originating will send to Viber/whatsapp gateway
2) Viber/whatsapp 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 and if the number is online, the call will terminated on Viber/whatsapp!.
4) if the number is not used in VIber/Whatsapp it sends 503 error and rerouted to other gateways .