Unfortunately, what you are asking is not possible. B4I would make this easy to do, but Apple block this as one or other policy that they have dictates that you cannot get the incoming CallerId.
On Android (B4A) I did it with ease, but my project was shelved as a result of not being able to do it with iOS.
Unfortunately not - it's in the OS. From what I can gather if you have a rooted device then there is a hack for it - but since I produce commercially I did not explore this route.