Regex for int phone no (simplified) + regex tester

hpl123

Hi all,
Here is a simplified regex for international phonenumbers and can probably be done in some other way but this works for my purposes.

The regex is:

 ^\+\d+$

I use it to validate phone numbers and the regex basically makes sure the number starts with a + sign and is followed by numbers only (no spaces, alpha or special characters) so numbers like these work:
+4612345678
+4512345678

I use it in different places but to give you an example of a rule where I use it:

If MATCHES(Reservation.Phone, '^\+\d+$')='No'
Then

I used the following regex tester to create/test the regex and works great:
https://regex101.com/

hpl123

Update:
This revised version also looks at number of characters and has to be 5-20 characters to be valid:

^\+\d{5,20}$