We have a mobile app ( IOS and Android ) and we need to implement a feature of VOIP Calling for customers . The workflow will be :
The User of the App will call a customer via VOIP server in UK to a phone number .
The app will call a API with date /time / details of the call for logging purposes. (success/fail)
The apps are developed in native code both for IOS and Android.
We need also recommendations for VOIP services / libs. If you implemented this in a previous app would be a great advantage.
The payment for the app will be done on delivery / after testing.