🚀 go-pugleaf

I've seen a lot of use on the net of
international phone numbers starting with
a + sign before the country code.  Is
this some sort of standard?  I have CCITT
Recommendations E.160 and E.163 through
E.167, and I don't see any mention of "+".

The question is this:  Is it plausible to
make an international telephone network
product that can accept full international
phone numbers (even for local calls) after
being configured for where it is in the world
phone network?  Seems to me yes, and now the
question is what syntax to use to indicate
an international phone number.

Thanks.

 --dave yost