Nope. In my world (and in my contact list), any phone number that doesn’t start with + is an invalid number 
Validating phone numbers with regex is a bit of a slippery slope. Every time you think you’ve nailed it, you’ll find another edge case that breaks it. And before you know it you’ll have something that looks like this:
/^
\+ [[:space:]]* [0-9] [0-9.[:space:]-]*
( \( [0-9.[:space:]-]* [0-9] [0-9.[:space:]-]* \) )?
( [0-9.[:space:]-]* [0-9] [0-9.[:space:]-]* )?
( [[:space:]]+
ext .
[0-9.[:space:]-]* [0-9] [0-9.[:space:]-]*
)?
$/xi
If you really want to do it, then you’re probably better off using an existing library.