See
However, unless you have a strong reason to keep it, I recommend removing the requirement for the extra zero, as it causes many problems.
If you don’t make or receive many international calls, you could set up your system so the extra zero is permitted but not required for domestic calls (but would be still needed for international). That would make displayed domestic numbers easier to read, and would allow for passing the proper caller ID on forwarded calls.
What city are you in? (There are area codes begin with 0244 but have an additional digit.)