How to create a SQL trigger to "normalize" a phone number?

Question

SQL Server

There is a field with a phone number in the database, it is a regular text field.
I didn't deal with triggers before, it is necessary that a field with a value of the form, for example "[phone] after 18" be converted to the form "791212312387" i.e. Throw out everything except numbers from the string. Is it possible to do so?

Answer 1

https://msdn.microsoft.com/en-us/library/ms186862.aspx