I need to validate phone number in PHP. I have made following regex, but I also need to it to accept numbers starting with plus char, how can I do that?
^[0-9]$
The regex you provided in your question (^[0-9]$) will only match a one digit phone number.
At the very least you probably need to add the + modifier to allow one or more digits:
^[0-9]+$
To add an optional + at the beginning, you'll need to escape it since + is a special character in regular expressions:
^\+?[0-9]+$
And finally, \d is shorthand for [0-9] so you could shorten the expression to
^\+?\d+$