At least in Germany a phone number always has a leading zero, e.g. landline 030 12345678 or mobile 0176 12345678 BUT for international numbers (-> E.164) the leading zero needs to be removed: +493012345678 or +4917612345678.

Therefor +490 should be invalid and, as far as I know, this applies to all numbers of the E.164 standard.