Last time, I had difficulties detecting phone numbers from different types of documents. The challenge was that I had to use different parsers to parse and extract the phone numbers. For example, to extract phone numbers from a Word document, I had to use a library that supports Word. Also, I cannot use the same library or logic to parse a PDF file. Ultimately, I need to maintain different libraries for different document types, which, as you can image, can lead to many issues.
It looks like this covers international phone numbers as well. Seems pretty interesting.