Here’s how to match a prefix code (a
+ or (00), then a number from 1 to 1939, with an optional space):
This doesn’t look for a valid prefix but something that might be a prefix. See the full list of prefixes
Then, as the entire phone number length is, at most, 15, we can look for up to 14 digits:
At least 1 digit is spent for the prefix
The numbers may contains spaces, dots, or dashes and may be grouped by 2 or 3.
With the optional prefix:
If you want to match a specific country format, you can use this search query and add the country, the question has certainly already been asked.