iOS Voice Calling App built on Twilio VOIP and AWS (or Azure)

I need to build a new voice calling app built on the Twilio VOIP platform and AWS (or Azure). The first version will be very basic, with more unique features in the future if the first project goes well. I'm looking for someone who really understands iOS, Twilio, and how to build out a proper and secure backend for this social/calling service. This person should be able to build an app which meets these requirements. If you're the right person, these requirements should feel "too easy" and you should want the app to do 100 more things besides this. But we'll start here: 1. App launches and asks for the user's phone number (US phone numbers only for version 1.) 2. User is sent a verification code via SMS, which they enter into the app. They are now logged in. 3. A user can enter the phone number of any other person to add them to their friends list. 4. If any two users have both added each other in the app, they are now friends. (This is the simple way of connecting people manually in the MVP. Future versions will have a more sophisticated invitation system.) 5. Friends in your list have a "Call" button next to their name in the app. Tapping the call button starts an app-to-app call using Twilio VOIP. 6. A call has only the most basic verbs (start, end) and states (connecting, in progress, ended). 7. Swiping right on a friend in the list reveals a "Delete" button which deletes the friend relationship. 8. Tapping the logout button on the app, resets the app. The user starts back at Step 1 if they relaunch.