[asterisk-users] + on Caller-ID

[Matt]

I've had this discussion in the office and with some vendors, but no
one has a solid answer, hopefully someone here does.

What is the proper way to format a caller-ID here in the U.S.?

Is it:
+15705551212
or is it
+5705551212

I've always seen it +15705551212, but as I understand it the country
code for the US is 011, which to me would indicate you put
011-570-555-1212 as the callback number.